Poisonous Gem is a pickup in Battle Fantasy, a mod for The Binding of Isaac.
Spawns a homing Ipecac tear in the direction that Isaac walks into it.
The spawning direction is indicated by a green line that spawns with the gem, constantly updating the tear's planned trajectory.
When the tear lands, spawns a puddle of green creep which deals 0.4 damage per tick and lasts for 1.5 seconds.
Can only spawn through the effects of Cursed Thorn.