So, you are just adding a poison equal to 33% of the damage you make. Sounds redundant
Less potent than poison. Its more like an 33% echo on the damage.
The buff is stackable so with 3 of these all your creatures effectively deal double damage.
The buff amount can be tweaked... its probably too low.
Its meant more as an in between on damage doubling and poison.
The opponent gets a turn to disrupt by using healing effects, but then it hits all at once.
Its actually closer to a delayed continual sky-blitz.