Boosts are special consumable items which you can use to deal additional damage to your opponents - monsters, arena fighters, covens, etc. Boost items can be used in all kinds of battles in the game.
Boosts can be purchased in the Shop, made in Alchemy, sent and received as gifts, or claimed as rewards in quests and battles. Items which could be used as boosts have a special bottle icon where the equipment place is displayed:
