A deck is composed of 59 cards : 1 hero, 8 events and 50 other cards (creatures, spells or fortunes depending on your preference).

A good guide when starting off in DoC is to have more creatures than spells or fortunes in your deck until you know how different cards work.
Bigger, more costly cards aren't always better: having lots of small creatures can help you get an early and decisive advantage over your opponent. choose your cards wisely!

About the hero and faction:
When you start of, you have the choice between 3 factions. Every faction has different heroes and one hero can only use cards for his faction and/or neutral cards.
A hero can only use spells of the same magic school as those he can control.

There are many different types of decks and strategies. Once you think you have understood how most the cards work, try checking out some of the decks in the Post your Deck sub-forum (here[forums.ubi.com]).

This will vary according to most people's preference, but here is possibly the easiest way for starting off in the game.

Do the tutorial then finish the campaign! This will give you a good amount of starting gold and seals. Go and do a few duels against other players to get to the next level, and, once you have enough seals buy the Box (or the Serious Box if you can).

This will give you loads of cards and should enable you to start getting a better rank.

Only buy Heroic Packs if you think you have enough creatures: if you buy a Heroic Pack too soon, you could get a hero from a different faction that you can't use yet as you don't have enough cards of that faction.

Only buy consumables (xp and gold boosts) if you know what you are doing. Buying Swiss tournament tickets early on may also be counter-productive.

You can also follow this chart from Tyrion to know what to buy!

When you click "Play" in the game, the first window that opens is the classic Duel mode: you will be paired up against other players of your level for straight forward duels. This is where you will get your constant flow of gold and experience points.

The Tournaments window will let you do 2 things: Jackpot Tournaments one day and Swiss Tournaments the next.

The Jackpot version will allow you to fight against other players one by one: you start off with 0 points and gradually work your way up if you can. You gain less gold per duel as it's put into a global Jackpot. The higher up the ladder you go, the higher the percentage of the jackpot you earn at the end of the day!

The Swiss version will allow you to enter an 8 player group. You will then do 3 duels and the best 2 players will get a nice prize. To enter a Swiss tournament you need Tickets that can be bought in the shop.

In general, I would advise you NOT to enter tournaments until you feel confident you know the game well, as you may face some very experienced and much stronger players!

Other modes from the tournames are ranked games and training games.

Ranked games (the big "find an opponent" button on the main page) matches you against a random opponent in the game, roughly of the same ELO (it can vary). This duels grants ELO, gold and experience at the end.

Training games are non-rewarding duels against your friends, AI, or others players willing to train without impatching their ELO. A good way to test out new decks and play with friends!

The Infernal Pit is and option where you can burn cards for gold and a small chance to win the special card on offer at that moment. The cards you burn will be gone forever (or until you find new ones in packs)... so don't rush into this.

Each card has its own value in gold, that you can get by burning them too!

The special card on offer changes randomly every 8 hours.

This option is only available after level 5!

The Altar of Wishes can be found right next to the infernal pit. It is our system to buy specific cards.

When opening packs, completing achievements or winning Community Tournaments, you can get Wildcards. Wildcards are tokens you can give to Nur, in exchange to a specific card in the Altar of Wishes.

Each card has its own cost, depending on its serie and rarity. A Common from base set is cheaper than a common from Forgotten Wars.

You unlock the Altar of Wishes when you get your first Wildcard.
At first, only the Base Set is available. After that, you have to obtain 200 cards from a serie to unlock it in the Altar of Wishes.

To gather more info, here are a few useful links:

Facebook Page[www.facebook.com]
Twitter
Twitch[twitch.tv]

English forums[forums.ubi.com]
French forums[forums-fr.ubi.com]