I recommend playing in easy/normal for your first playthrough, as the game can be pretty hard if you don't know which skills to choose.
You can try do to the "Abstinent" achievement during this playthrough (I did it this way), but it is not advised.

Playthroughs : 2 at least / 3 recommended
Duration : around 40 hours

Just follow the story, and these achievements will unlock.

Awaken



In The Face?!



The Source of the Evil



The Demon Master's Heritage



Demon Slayer



There Can Only Be One



Xarfai's Pledge



Self Conflict



Mishkara's Caprice



Back to the Nether Hells



Farewell, Sister



Father!



Fall of the Prophetess



It Ends Where It Began

At some points in the game, you'll have to make choices. Nothing in this game is as simple as black and white, it's not "Good vs Evil". Each choice will impact the game, but it won't change the end of the game. If you unlock one achievement, you can't have the other, unless you reload a save or do another playthrough. Since you need at least 2 playthroughs, no need to worry.






The Last Meal / Mercy Before Justice





Serve and Protect / Deceive and Disguise





Asfaloth's Adversary / Mishkara's Enemy





Blakharaz' Sword / Tasfarelel's Shadow





Son of Man / Will to Power





Steadfast / Wanton





Götterdämmerung / Iconoclasm





True Love / Hells Can Wait
For the "Hells Can Wait" achievement, you'll need the talent "Fast Talk" level 7.

Chain Artist / Frenzied Chain Artist / Master Chain Artist

Achieved a chain of (5 / 12 / 24) blows.
The longer the chain of blows, the more essence is stored up. The chain of blows is broken when you get hit, or when the attack button is pressed too often during a series of normal attacks (more than 1 time during an attack). Throwing knives is a good way to build up the chain.

But not enough for the 24 blows achievement, as you won't have enough stamina.

How I did (did it with Cassio, don't know if it will work with other bosses) :

During a boss fight, use the poison spell (third from the left). First level is good enough. It won't make much damage, but this spell doesn't cost much to use (0.8 ES per second) and it will stop the boss while you hold the spell, allowing you to easily achieve a chain of 24 blows.





Pactereer / Shadowstalker / Warrior

200 spells / dodges / warrior moves. No problem here.





Persevering

10 enemies killed with ranged weapons. Doesn't need to be in a single fight. There's plenty of occasions, no problem here.





Untouchable

Some fights are tough, but some others are incredibly easy. If you're having difficulties, dodging and throwing knives will do the trick.

Prepare for Adventure!

At some point near the beginning, the game will prompt you to invest some Adventure Points in a Talent. Choose whatever you want, the game will give you many opportunities to gain that achievement. No problem here.





Eager Student / Grandmaster

Raise a talent to rank 4 / rank 7. If you're having difficulties to understand how Points and Skills Trees work, here is the thread you're looking for.





Godlike

Raised an attribute to its maximum. Attributes are rather expensive, but you'll surely have enough points near the end of the game.

Dilettante / Experienced / Apothecary

10 / 50 / 250 potions or poisons used. The last one is a bit tricky, you can't use your potions then reload your save. So buy all potions you can find, search everywhere, craft them if you can. For information, I had enough potions without crafting.

Important : These achievements DOESN'T STACK through multiple playthroughs. It has to be in a single playthrough.





Abstinent

Play the whole game without using a single potion. Once you know the game (and the enemies / bosses weak points), it's pretty easy. But it's not recommended to do this achievement in your first playthrough, even on "Easy".

Belhalhar's Minion

Played Demonicon through in "Hard" difficulty





Belhalhar's Butcher

Played Demonicon through in "Nether Hellish" difficulty. You need to finish the game on "Hard" difficulty first, in order to unlock "Nether Hellish" difficulty.

In Demonicon, there's a lot of talent and skills, and it's perfectly normal not to know where to invest your hard earned points. Here are some general tips, as well as some tips on how you can spend you points.


About Gift Points (GP) and Adventure Points (AP) :

The number of GP you earn, allowing you to buy new spells, depend on the spells you use. The more you use you spells, the more Gift Points you'll earn.
I read somewhere that AP are changed into GP, but there are plenty of AP, so don't worry. Even if you're focusing on that, you won't have enough GP to buy all spells, so you need to choose wisely.


Recommanded spells :

Demonic Aura : A must have. It'll increase your speed by 130% at low level, and create a shield around you at high level. Makes you almost invincible at the end of the game if maxed out.

Ice Spear : Basic spell. Always useful, but a bit slow to cast. Freeze enemies, then follow with a physical attack. Good strategy for almost every fight, including bosses.

Poison Spell : Useful against some enemies. Drawback : you can't move while using this spell. Not recommended against multiple enemies.


Recommended physical attack :

Lunge : Quick attack. Once maxed out, will pierce through enemies armor, dealing massive damage. Fill the Essence bar very quickly. Good combination with Ice Spear (Freeze then strike). Only usable with Bladed Weapons.

Roundhouse : Useful when many enemies surround you. Once maxed out, it will repeal and stunt enemies, allowing you to chain with another attack.


Basic tips :

Don't try to counter, it's not worth the shot. Dodge instead. Everytime.
Freeze, then hit with physical ability.
If you can't freeze your enemy, dodge then attack with physical ability.
If Demonic Aura is unlocked, use it at the beginning of the fight.

You can't damage him with your weapon. Use your newly acquired "Gift" on him. When you run out of essence, attack zombies to fill your bar.

As the previous "boss", you can't damage him without spells. Same strategy here : cast a spell to take down his shield, then hit him as many times as you can. Repeat until he climbs on a platform. Cast spells while avoiding rocks.

Get rid of his mens first, they're the bigger danger here. Now you can bash him all you want. Some zombies are toughter to kill than others, but it's not a big problem.

Best strategy here is to bash him with your fighting abilities while he has no shield. He will be dead in no time.

First real boss fight. Too quick to fight normally. Cast an ice spell, but hold it. When it's coming at you, get ready and fire the spell at the right time to freeze it, then hit it with all you've got.

Don't know if it's a bug or not, but I wasn't able to freeze the demon once it flies away then land again. If it happens to you too, use combat abilities. You'll be able to hit it once, but it will hit you too. Fortunately, the demon doesn't have that much health.

A loooooong fight. Here is the strategy I used : Dodge, then when he's walking toward you, freeze him and hit him with a combat ability. Rinse and repeat.

If you're not confident enough, you can throw knives.

Once his health is low, he will go to the center of the room and restore his health. Hide behind a statue. The beam he fires will destroy it.

Okay, now do the whole thing 3 times again with the 3 other statues, and you're done.

Your are your own opponent here, meaning your enemy can use your skills and spells. Dodge attacks, freeze and hit with combat abilities.

Avoid its smashs. Freeze and hit. Rinse and repeat. The end.

Ghamat will turn into a big (but slow) monster. Use your throwing knives to make zombies explode, and destroy tentacles. Do the same with him once he moves, and the fight will be quickly over.

This fight made me cry.

Cassio can't be freezed, she creates clones that can attack you, she teleports right in your back, she invokes fire demons.
Three phases here :

First phase :
Cassio will create several clones. Kill them but keep 2 of them alive, or they will all respawn. She will teleport here and there. Once she's near you, if she attacks you, use a combat ability to stop her attack, then dodge. Repeat until she revokes her clones, then summon another clone.

Second phase :
2 clones here, teleporting and using melee attacks. Use your combat abilities to damage them, or you can use the poison spell to stop them, they will be unable to move this way. Once you kill a clone, the remaining one will summon another clone to replace the one you kill. So you need to damage both clone equally, so that when you kill one you can kill the second quickly before the summoning is complete.

Third phase :
When clones are dead, Cassio will reappear ... along with 4 fire demons. No need to attack them, even if you can kill them they will respawn immediately. Concentrate all your attacks toward Cassio. As usual, she will teleport here and there. Like in the first phase, use your combat abilities or the poison spell to damage her. Poison spell is efficient against fire demons as well.

If you run out of stamina, just run in circle and avoid attacks.

Hard fight, but less difficult than the previous one.

Three phases here :

First phase :
Kill all mages and summoned demons, then break the 2 green cristals. If you're too slow, other mages will arrive.

Second phase :
Azaril will float in the air, and summon 3 poison demons. You can kill one of them, but no more or they will respawn. Use your throwing knives to damage her and make her fall on the ground. Damage her with combat abilities (more damage in less time), until she flies away. Rinse and repeat until mid health.

Third phase :
Azaril revokes poison demons and summons a fire demon. The fire demon is not a big threat here, as it will only cast fireballs onto you. Just make sure not to stay near it, or its fire aura will damage you.

Azaril will teleport sometimes, but she will mostly cast 3 spells, one after another.

- Ice spell, which will slow you down a lot.
- Wind spell, dealing damage and repealing you.
- Then a fire spell which will bring up lava in a large zone. Avoid this zone, or you will take huge damage.

As usual, use your combat abilities to damage her while avoiding spells. Rush just after she is done casting spells, and it should be alright.

You're not alone in this fight, but you'll have to fight several demons at once. Destroy each cristal, but keep on eye on the big demon in the center of the map, as it will throw rocks and fireball on you. You can let your partner do the fighting, while you attack from afar and stab demons in their back, but beware of their fire aura (use ice spell to stop it) and beware of the demon avatar.

After the fight with Azaril, it'll be a piece of cake. The fight end when you destroy the last cristal.

Congratulations ! You finish the game !