The icon used in one of my old maps as the Assassin's "Lethal Poison", an ability similar to Shadowstrike, except it throws a bottle of poison, evidently. Could be used as an item if needed of course.
On the passive and disabled buttons, the bottom's darkness looks noticeably larger than on most other icons, if this is a problem, I could add more glow to the bottom of the bottle.
Keywords:
Bottle, of, Poison, Skull, Crossbones, Do, Not, Touch, Death, Assassin, Shadowstrike, Green, Spell, Lethal, Deadly, Throw.