Focus Crystal

The Focus Crystal is an item introduced in Risk of Rain 2.

Hitting an enemy within 13 units of the character will apply a 1.15 (+0.15 per stack) multiplier to the damage dealt.

The 13 units are measured as a sphere around the character.

This item is extremely powerful to stack as Mercenary and Loader since most of their attacks will fall within the 13 unit range of the Focus Crystal, meaning that it is essentially a consistent damage buff. Other characters will be frequently attacking from far outside of the activation range.