Foul Antidote

At the beginning of your upkeep, remove a
poison counter from target player. If you do,
Foul Antidote deals 2 damage to you.
{4}: Remove a poison counter from target player.
If you do, Foul Antidote deals 2 damage to that
player. Activate this ability only once per turn
and only at sorcery speed. Any player may
activate this ability.