First off, some information that may be valuable to achievement hunters:

• Achievements from GOG will not be transferred. That's one of the reasons why I am writing this guide.
  
• Achievements can only be unlocked in online matches, and not against bots.
  
• However, as of now, matches against friends count as online matches! Therefore, you can play a friend and try to achieve a certain game status together. Some achievements will be a lot easier to obtain like this.
  
• Players that come to Steam-Gwent with a lot of progress already will have trouble unlocking some of the achievements (no option to re-play the tutorial, no trigger to get leader skins, etc.). I will describe possible solutions for the achievements individually, but I can already tell you that in some cases there's only one option left: creating a second GOG account.
  
• How long it will take you to get all of the 46 (formerly 50) achievements is highly dependable on whether you already played a lot of Gwent before or not. Personally, I had them in 20-25 hours. However, I already had a full collection and was on prestige 2 when first playing on Steam.
  
• For most of the deck-related and mechanic-related achievements I was assuming that the player has a full collection. I'm quite positive that all of them can be done with different (cheaper) decks, it will just be more difficult. If you need advice on possible card replacements, hit me up.
  
• Don't confuse rank with level. Rank refers to your rank on the ladder and goes from 30 all the way up to 0. You can climb by playing ranked matches. Level on the other hand refers to your account level and goes from 1 to 60. After completing that, you start over at level 1 again, but on a new prestige level.

In the following I will try to describe possible solutions for each of the 46 achievements.

These achievements don't need a lot of explanation. Most likely, you will get them eventually.


Complete the basic tutorial.

This is the very first achievement for new players. It will be unlocked right after finishing the tutorial. The 3 practice matches after the tutorial are not necessary for this.
For players that already completed the tutorial on another platform, there is no option to re-play it on the same account (as of now). That's why I had to create a second GOG account. You can easily switch the account by logging out of the current one (in-game option). Logging in with the new one will make you play the tutorial, because that account is new to Gwent. You should get the achievement right after finishing. Do not skip though!


Play a bronze and a gold card in a multiplayer game.

Put some gold cards and some bronze cards in a deck, eventually you'll play one of each.


Play one ranked game.

As far as I know, you can't play ranked games from the start, but as soon as you can (probably when you reach rank 25), just play one.


Finish 3 online matches.

Play online matches.


Have a winstreak of 3 in any multiplayer game mode.

You need to win 3 games in a row against other players. That will happen as soon as you play a decent deck for your MMR.


Reach level 15.

This will unlock eventually as well. If you were already higher than level 15 before playing on Steam, it will unlock with the next level-up. If you already reached the max level, you can create a new GOG account and level that one.


Reach level 40.

Analogically to the Milestone achievement, you will get this after playing for some time. And yet again, if you already reached that level before, it should trigger with the next level-up.


Reach Prestige 1.

This is the equivalent of reaching (and completing) level 60. You will start over at level 1 again, but on a new prestige level. The same rules as for the Milestone and Munchkin achievements apply.


Reach Rank 20.

If you keep playing, rank 20 should be relatively easy to reach. Sticking to one faction early on and building a deck around your strong cards will most likely help.


Get a draw in a multiplayer game.

A draw is not the most common thing to happen, but I would say out of 30 games there's probably at least one tie. Otherwise you can easily get this when playing a friend.


Play a maximum number of units into any single row.

This will probably be unlocked "accidentally" but if it doesn't, just play all your units on the same row. Playing cards that spawn additional units may help.


Win a round and game, after losing by 20 points.

There are certain deck archetypes that are more suitable than others at getting this, but most likely it will happen at some point anyway. A friend can also help here.


Win a game with 2 cards remaining in hand.

This should trigger as soon as your opponent forfeits while you still have 2 or more cards in hand.


Destroy a unit with Zeal before it's triggered.

Unless you are playing a friend who is helping, there would only be some specific cards that could help unlocking this (like Incinerating Trap). But you'll eventually get your chance, I'm sure of it.


Win a Regular Battle without redrawing any cards.

You can speed up getting this by refusing to mulligan any cards. But most likely there will come a game in which you have the perfect hand 3 rounds in a row that you're gonna win. A friend can also help here.


Have card advantage of 3 cards.

This is another one that will probably happen at some point. If you want to improve your chances, try a deck where you play a lot of points and potentially engines in the first three turns, then pass. Maybe your opponent will try to overcome the lead and go some cards down.
The easiest method by far is to work together with a friend in a friendly match. Notice that it will only trigger if your opponent is actually 4 cards down at some point (say you have 7 cards and they have 4, then it should trigger when they play one more card).


Send "GG" 50 times.

Make sure you always send a "GG" to your opponent at the end of the game end then you should get this after 50 online matches. If you already unlocked this on GOG, it should trigger with your next "GG" that you send.


Smash 100 kegs.

Translated to other card games this would read "Open 100 card packs". As long as you regularly spend Ore on kegs, this should automatically pop after some time while expanding your collection. However, it seems that not all kegs count towards this. Some keg types are probably newer than the achievement. Ultimate Kegs should do the trick, though.
Gwent is a generous card game. While you can pay real money and get this really fast, you will get a generous amount of Ore by completing daily quests, spending Reward Points, being successful in the Draft Mode and also by getting "GG"s from your opponents.


Destroy a Legendary enemy with a Common ally.

It happens all the time that legendary units die from common cards. Note that a common ally doesn't have to be a unit, it just has to be a card of common rarity. So you can unlock this by killing a legendary enemy of 5 or less power (e.g. Vernossiel, Cerys an Craite, Triss: Telekinesis, Damien de la Tour, etc.) with Alzur's Thunder, for example. If you're having trouble, a friend can probably help.

Collect 50 unique cards from 1 faction.

This can be done faster if you only buy kegs and craft cards from a certain faction, but eventually you'll get this anyway.

! Warning: Known to be bugged. I cannot guarantee that my solution will work. !

Equip a vanity leader skin, an avatar, a border and a title.

You can equip an avatar, a border and a title by clicking on your profile on the top left and then on Trinkets. Equip something else than the defaults (what you have equipped after the tutorial). Additionally, before starting a game, you can equip a leader skin. From what I know, you should choose a leader that is not a faction default.
You will probably need to play a game with the different leader skin equipped - and, apparently, it might only work if you do this with a very old deck or a starter deck.
If all of this did not make you get it, you can still try to create a second GOG account and farm some vanities there.


Mill 50 cards

As of now, duplicate cards (more than 2 of the same bronze card and more than 1 of the same gold card) will get milled (turned into scraps) automatically. That means, you'll just have to wait until you opened enough duplicate cards and then enter the Deck Builder. It will happen faster if you only buy kegs from the same faction.
If you already milled more than 50 cards on other platforms, one more mill should trigger this.


Transmute a card.

To do that, enter the Deck Builder, right-click a non-premium card and choose Transmute. Note that some cards don't have this option because their premium version is linked to a certain reward. Also, you will need enough Meteorite Powder to transmute the card of your choice.


Own at least 150 premium cards.

If you already had a collection of at least 150 premium cards before playing through steam, I believe this will unlock with your first login. Otherwise, transmuting a single cards should be more than enough.
New players can either spend real money on Meteorite Powder or collect it by spending Reward Points, complete quests, etc. The cheapest cards are Commons (bronze cards with a white triangle on the top left) with a cost of 30 Meteorite Powder to transform into premium. It has been confirmed that the cards don't have to be unique, duplicate premium cards also count towards this.

! Warning: Known to be bugged. I cannot guarantee that my solution will work. !

Obtain at least one leader from each faction.

The wording of this achievement is a bit off. You'll need at least one additional leader (besides the default) for each of the first five factions (Monsters, Northern Realms, Nilfgaard, Skellige and Scoia'Tael). You can unlock these in the reward book on the first page. Defaults are:

• MO: Eredin
  
• NR: Foltest
  
• NG: Emhyr
  
• SK: Crach
  
• ST: Filavandrel

These will not count towards this achievement.
As mentioned above, this achievement is known to be bugged. If you already had an alternative leader for each faction before playing first through Steam, there's a chance that it won't unlock. And if you already had all alternative skins, there's only one way left to try and make it trigger: create a second account. There, you'll need to grind 50 Reward Points to unlock an alternative leader for each of the five starting factions. This achievement should then be yours. However, I cannot guarantee that and I don't know what makes it work for some but not for others.

Resurrect at least 5 cards in a match.

Best Faction: Skellige
Leader Ability: Blaze of Glory
Core cards: Crowmother, Sigrdrifa's Rite, Tuirseach Skirmisher x2, Morkvarg
Additional help: Birna Bran, Coral, Heymaey Skald x2
How to fill the rest of the deck: thinning cards, Skellige cards, cards that destroy your own units (to kill Crowmother), alchemy cards
What to do: Play Crowmother in turn 1, if possible. Discard the Skirmishers and Morkvarg with Coral or Birna. Revive any Skellige card with Sigrdrifa's Rite. Resurrect Crowmother with alchemy cards.
Note: Only cards that are summoned from the graveyard count towards this achievement. Freya's Blessing won't work.


Destroy a unit that is immune.

Best Faction: Monsters
Leader ability: -
Core cards: Alpha Werewolf, Werewolf (x2), Endrega Warrior
Additional help: Frightener: Dormant
How to fill the rest of the deck: tutoring and thinning cards
What to do: Play one of the cards with the Immunity tag, then, next round, play an Endrega Warrior next to it.


Spawn five allies in a single turn.

Best Faction: Monsters
Leader Ability: Arachas Swarm
Core cards: Arachas Nest x2
Additional help: Whispess: Tribute, Royal Decree
How to fill the rest of the deck: thinning cards
What to do: Play Arachas Nest. Because of the leader ability, a 5th Drone will spawn.
Note: It has not been tested whether the leader charges count towards this achievement.


Start a round with 10 points on the board.

Best Faction: -
Leader Ability: -
Core cards: Shupe's Day Off, Runemage
Additional help: Arcane Tome, Royal Decree, Matta Hu'uri, Oneiromancy
How to fill the rest of the deck: no duplicate cards (to activate Shupe)
What to do: Play Runemage, then Shupe's Day Off for Shupe: Knight and choose the Resilience option.
Note: If you don't own Shupe's Day Off, look for other units with the Resilience keyword in the deckbuilder. You can also combine Ciri: Nova with Vandergrift, for instance.


Play 5 cards in a single turn.

Best Faction: Nilfgaard
Leader Ability: Double Cross
Core cards: Royal Decree, War Council, Menno Coehoorn, Dandelion: Poet, Marching Orders
Additional help: -
How to fill the rest of the deck: thinning cards, tutoring cards
What to do: Try to get a chain as long as possible. Example: When having Marching Orders and Royal Decree in hand, you could play a chain like this: Royal Decree -> Dandelion: Poet -> Marching Orders -> Menno Coehoorn -> War Council.
Note: If you don't own all of these cards, nowadays there are also other good options. Golden Nekker plays three cards on its own, for instance. If you search the word "Play" in the deckbuilder, you'll find a lot of cards that help with this. If you only manage 4 cards in a turn, use the leader charge for a 5th one.


Destroy a Doomed enemy with a Doomed ally.

Best Faction: Skellige
Leader Ability: Patricidal Fury
Core cards: Freya's Blessing x2
Additional help: Ermion
How to fill the rest of the deck: bronze units that let you deal targeted damage
What to do: Let one of your bronze units that deal damage die. Use then your leader ability, revive the bronze card with Freya's Blessing and kill one of the Sirens.


Fill your opponent's side of the board with row effects.

Best Faction: Skellige
Leader Ability: Rage of the Sea
Core cards: Biting Frost x2, Impenetrable Fog x2, Torrential Rain x2, Scepter of Storms, Avallac'h, Melusine
Additional help: Avallac'h: Sage (to get out the Scepter)
How to fill the rest of the deck: thinning cards
What to do: As soon as you have two of the core cards in hand, play one of them and the second one in the following turn (on the other row). Or you can just use a leader charge.


Boost a unit to over a 30 points in a multiplayer game.

Best Faction: Nilfgaard
Leader Ability: Toussaintois Hospitality
Core cards: Buhurt x2
Additional help: False Ciri, Milton de Peyrac-Peyran, Guillaume de Launfal, Cahir Dyffryn, Oneiromancy, Menno Coehoorn
How to fill the rest of the deck: thinning cards
What to do: Play a unit, then play the Buhurt cards and additionally the Buhurt from your leader. This is already a boost of 27 if you always boost the same unit.

Win a game using 15 special cards.

Best Faction: Nilfgaard
Leader Ability: Double Cross
Core cards: Stefan Skellen, Lydia van Bredevoort, Triss: Telekinesis, Aguara: True Form
Additional help: War Council, Alzur's Double Cross, Marching Orders, Royal Decree, Menno Coehoorn, Artorius Vigo, Impera Brigade x2, Xarthisius, Bribrery
How to fill the rest of the deck: as many Tactics as possible
What to do: Try to play every special card in the deck with the help of thinning. Additionally, you'll have to try and get additional specials with some of the units or with the leader ability in order to reach a total of 15 played cards, because the maximum for special cards in a deck is 12.


Fully deplete your deck.

Best Faction: Skellige
Leader Ability: Blaze of Glory
Core cards: Lippy Gudmund
Additional help: Royal Decree, Oneiromancy
How to fill the rest of the deck: -
What to do: Play Lippy as the first card and your deck will be empty (unless you tutor him). Then you can just pass and draw whatever was put back in the deck.
Note: There are other good hyper-thinning options, like Troll Porter, Magic Compass, Golden Nekker, Birna Bran, etc.


Have 4 artifacts in play at any time.

Best Faction: -
Leader Ability: -
Core cards: Artifacts in general (you can filter for Artifacts in the Deck Builder)
Additional help: Avallac'h: Sage
How to fill the rest of the deck: thinning cards
What to do: With the help of thinning and tutoring, try to get 4 artifacts on the board.


Destroy 3 or more units with a single card.

Best Faction: Skellige
Leader Ability: Patricidal Fury
Core cards: any card that deals at least 1 damage to 3 units on a row
Additional help: Royal Decree, Arcane Tome
What to do: Use the leader ability to spawn 3 sirens, then play a damage card and kill them.


Win a round with only Order units.

Best Faction: Northern Realms
Leader Ability: -
Core cards: Order units in general
Additional help: Royal Decree
How to fill the rest of the deck: Order cards
What to do: It's probably easiest if you overcommit in round 1 with strong Order cards like Prince Anséis, Seltkirk of Gulet, Bloody Baron, etc. to force your opponent to pass.


Win a multiplayer game without Golden cards in your deck.

Best Faction: Monsters
Leader Ability: Fruits of Ysgith
Core cards: Selfeater x2, Gan Ceann x2, Incubus x2, Witch Apprentice x2, Lesser Witch x2
Additional help: -
How to fill the rest of the deck: Relict cards
What to do: Start off with one or two Selfeaters, then spam your strong Relict bronze cards for a lot of points. Make use of the Witch Apprentices as soon as Sabbath is activated.
Note: Of course it is easier to just win with a bronze deck against a friend. If you try this in actual matches you'll probably need some patience because it won't work in every match-up. Other archetypes that could work are Dwarves (Scoia'tael) and Thrive (Monsters).


Win a battle without killing any of the opponent's units.

Best Faction: -
Leader Ability: -
Core cards: point-slammy, greedy cards that don't interact with the enemy
Additional help: -
How to fill the rest of the deck: -
What to do: Just play for points and refuse to use damage cards (or at least don't kill with them). Movement cards are allowed.
Note: Some suitable archetypes are: Renfri Invigorate, Saskia: Commander + Harmony, Triss: Meteor Shower + Relicts, Northern Realms Knights.


Use 10 order charges in a single turn.

Best Faction: Northern Realms
Leader Ability: Uprising
Core cards: Vissegerd
Additional help: Voymir, Caravan Vanguard x2, Immortal Cavalry x2, Royal Decree
How to fill the rest of the deck: Boost cards, Inspired cards
What to do: Play units and boost them until you have 9 boosted units on your side of the board. Then you can play Vissegerd and use all his 10 charges.
Note: A well-built Traveling Priestess deck will also do the trick. You can also try to play Order units and just hover the charges (save them until you have enough).


Order at least 3 units in a single turn.

Best Faction: Northern Realms
Leader Ability: Stockpile
Core cards: Carroballista x2, Reinforced Ballista x2, Siege, Battering Ram x2, Foltest's Pride
Additional help: King Henselt, King Radovid V
How to fill the rest of the deck: Warfare cards, Resupply cards
What to do: Play at least 3 Resupply units on your back row, then use leader charges to get them all off their cooldowns.


Deal a total of 30 damage to units in one multiplayer game.

Best Faction: Skellige
Leader Ability: Blaze of Glory
Core cards: Jutta an Dimun, Highland Warlord x2, Gutting Slash x2, Stunning Blow x2
Additional help: Harald an Craite, Freya's Blessing x2, Blood Eagle
How to fill the rest of the deck: Raid cards
What to do: Play your Highland Warlords as soon and as often as possible, then deal some juicy damage with your Raid cards. Combine your leader with Jutta an Dimun for another potential 12 damage.


Control at least 5 cards with the same power.

Just re-use the deck from the We Are Legion achievement. You can also just use all of the Arachas Swarm leader ability charges to have five 1 power units.


Win the final round of a multiplayer game by 50 or more points.

I would argue that this is a deck-related achievement because only certain decks can get ahead so far in points. Of course you'll need some luck with the match-up. Possible decks are:

• Rage of the Sea (Melusine, Messenger of the Sea x2, Rioghan the Undying, Fulmar)
  
• Renfri Vampires (Renfri, Regis: Reborn, Fleder x2)
  
• Northern Realms Knights (Damsel in Distress, The Maiden's Shield, Knight Errant x2)

Instead of trying to get this achievement with a certain deck it may be easier to unlock this in Seasonal Mode (if it supports high point generation). Also, playing a friend would make this a lot easier.

Note: The latter 4 of the achievements below have been deleted, reducing the number of gettable achievements from 50 to 46. This was done due to the deletion of the Arena and introduction of Draft mode. "Baptized With Fire" stays and is still easily doable in Draft mode.


Play a card from 5 different factions during a match.

This should be quite easy to obtain in the Arena. Just draft some diverse cards and eventually you'll have a round in which you play cards from five different factions.


Play one arena game.

Just start an Arena run (it will cost 150 Ore to enter), draft your deck and play a game.


Finish a contract with Gaunter (complete an arena run).

After entering the Arena, play until you either have 3 losses or 9 wins. The run will be over and you will get this achievement. I belive it even triggers when you break the contract.


Complete an arena run with at least 6 wins.

This probably requires you to have a somewhat deeper understanding of the game. It is helpful if you know a lot of cards and it will come in very handy if you know all the mechanics and when to pass. However, with a strong deck it should be possible for new players as well.


Have 3 copies of the same cards in an arena deck.

This is probably one of the toughest achievements to get. With over 1000 cards in the game, it has become difficult to get multiple copies of the same card in an Arena deck. While pairs are quite common, you'll most likely need some patience, Ore and luck to get a triple.
I did not want to wait for this to happen by chance, but instead I wanted to "grind" it. I started an Arena run and drafted my deck. In the end I would break the contract immediately if I wasn't successful. I continued to do this until I got lucky.
The draft is fairly easy: Look at the 4 options, check whether you already have one of them, otherwise pick a random card. I spent something like 4000 Ore until I got this achievement.