A Boost in an immediate advantage. Once revealed, a Boost token in used up: it provides the Krosmaster using it with its advantage, and is then removed from the game. As long as it is face-down, a Boost token does not have any effect.
A Buff is a temporary improvement. When a Krosmaster uses a Buff token, turn in face-up on the character card: they will then benefit from the Buff effect until the start of their next turn. At that point, you should remove the Buff token from the game.
Equipment is a permanent improvement. It takes effect as soon as the Demonic Reward token is turned face-up, and stays that way until the end of the game. Once revealed, it is impossible to separate a character from the Equipment token. There are 5 types of equipment: Weapons, Sets, Pets, Technique and Dofus. A Krosmaster can only have one token of each type of Equipment face-up on their card. If a Krosmaster already owns a piece of Equipment, they cannot reveal another one of the same type.