Drops fall from kills for a short, powerful boost. Runes are bought at Rune Benches and last the whole run (lost on death). Gun runes enchant the weapon you're holding; player runes are passive. Icons and effects are the game's real ones.
Fall from zombies · timed · shown with a fading HUD timer
On-hit bullet upgrades · applied to the weapon you hold · stack per gun
Passive boons · max three at once