Lash of the Siren's Tail

Overflow (If there are eight or more noncreature
spells in your graveyard, the battlefield becomes
flooded for the rest of the game.)
If the battlefield is flooded, create a 3/3 green
and blue Serpent creature token with submerge.
Then put a +1/+1 counter on target creature
you control. It deals damage equal to its power
to target creature you don't control. (A creature
with submerge can't be blocked while the battlefield is flooded.)