Stun Grenade

The Stun Grenade is a new item in Risk of Rain 2.

The gives every shot a 5% (+5% per stack) chance to stun most non-boss enemies, interrupting most attacks and locking the enemy in place for 2 seconds. It is one of the only items in the game with Hyperbolic Stacking, meaning that as the player collects more the item adds less and less chance to stun. The chance to stun is also multiplied by the Proc Coefficient.

Math
The chance to activate is determined by the formula