i misunderstood the "if it hits" part then. so the damage would be over and over stacking, so if i understand this correctly, this would be a five turn scenario:
net damage done to you | stacks of poison on them | net damage done to them
3 | 6 | 6
6 | 12 | 18
9 | 18 | 36
12 | 24 | 50
15 | 30 | 80
This is why it is OP. However this is the suboptimal usage the regular usage (with a Blessing|Chaos Power) would be
net damage done to you | stacks of poison on them | net damage done to them
6 | 12 | 12
12 | 24 | 36
18 | 36 | 72
24 | 48 | 120
Why not change it to Poison=damage dealt? ("Attack + 1" is unecessarily complex when "Attack" would be fine)
Poison=damage dealt with 1 Chaos Power
net damage done to you | stacks of poison on them | net damage done to them
6 | 6 | 6
12 | 12 | 18
18 | 18 | 36
24 | 24 | 50
30 | 30 | 80
36 | 36 | 116
Although Trojan Horse would work better as a weaker cheaper version that can be played earlier than that.