Infusion (Risk of Rain 2)

Not to be confused with the first game's version, Infusion. The Infusion is a returning unlockable item in Risk of Rain 2. The user's max life is increased by 1 whenever they kill an enemy, up to 100hp per stack. Having more than one item won't increase the amount of life gained per kill.

The Challenge "Slaughter" unlocks this item.

The user has to deliver the killing blow themselves or have the enemy die to an effect they made for this item to work. Enemies killed by Auto-Turrets increase the Turrets max life instead, and kills made by drones or ghosts won't give the bonus.

Visually this item is shown as a series of three red vials on the characters right thigh.

With the Transcendence lunar item in unison with Infusion, it seems that there won't be a max life increase cap anymore, as ur health pool is capped at 1, while the rest is converted into shields.