Gameplay is centred on your character, a warlock. Your warlock is your avatar. The warlock can summon abyssals to fight, he can cast spells, he can attack, he can use equipment and he can take damage. If your warlock runs out of health, the battle is over and you lose.
The field for your side of the battle will look similar to the rough concept below:
The top row shows the slots where you can summon up to a total of five abyssals from your hand. The bottom row from left to right shows: your deck (totalling up to 40 cards), your current equipment for your warlock, your warlock himself, the ritual you currently have active and, finally, the abyss (discard pile).
In order to play cards, you need to use up parts of your soul. You start with 1 soul at the beginning of battle and each turn it recovers, but you can also gain more. The increase each turn will be developed as the game gets balanced. All cards require soul: abyssals, spells, equipment and rituals.
The turn order is as follow:
  1. 1.
    The player to move first is randomly chosen.
  2. 2.
    Player 1 draws.
  3. 3.
    Player 1 uses whatever soul they choose to summon creatures and take actions (e.g. attacking).
  4. 4.
    Player 1 chooses to end their turn.
  5. 5.
    Damage over time effects take place.
  6. 6.
    Regen effects take place.
  7. 7.
    Player 2 begins their turn and repeats the same steps as Player 1 from Step 2.
This continues to alternate between players each turn. Please note that when an abyssal is first summoned, it is unable to attack. Player 1's warlock cannot attack on the first turn, whereas Player 2's warlock can. This is to provide a counter to the fact that Player 1 has the first mover advantage.
If a player runs out of cards, their warlock will be reduced to zero health after three turns, regardless of any recovery effects. Battles aren't expected to typically last this long, but it's a failsafe to prevent a stalemate scenario.