no thats not what it does. it (unupped) takes 10 health from your opponent (no poison or anything) and then gives your opponent 1 regeneration counter and gives the caster 1 poison counter. the regen counter does not take away all poison.
Each turn it:
Costs 1
Damages the opponent 10
Heals the controller 10
Poisons the controller for +1 poison
Gives the opponent +1 regeneration
This is cumulative per turn so if you use it twice
Costs 1
Damages the opponent 10
Heals the controller 10
Poisons the controller for +1 poison
Gives the opponent +1 regeneration
End turn
The Controller takes poison damage [1]
The opponent regenerates [1]
Costs 1
[2
total]
Damages the opponent 10
Heals the controller 10
Poisons the controller for +1 poison
Gives the opponent +1 regeneration
Current Status during second turn:
Opponent: 10 damage, 1 healing, 10 damage = -19 hp
Opponent: 2 Regeneration counters
Controller: 10 healing, 1 damage, 10 healing = +19 hp
Controller: 2 Poison counters
Net Hp swing = Controller - Opponent = 19 - (-19) = 38
That poison line in the tables was referring to the poison on the controller.
