In "The Book", the grenade plays a key role in gameplay. Essentially, it has two functions: amplifying weapon damage and providing ammunition.
When you throw the grenade at an enemy, they take on a bright orange hue: the grenade has taken effect. In this state, enemies suffer additional damage from weapons. The value of the damage multiplier depends on the level of the grenade itself, which can be increased in the game.
When an enemy is killed under the effect of the grenade, they will release ammunition for the available weapons.