Merfolk Multitude

Submerge (You may have this creature enter the battlefield with a -1/-1 counter on it. It can't be blocked as long as it has a -1/-1 counter on it.)
Whenever one or more lands are flooded, create a token that's a copy of Merfolk Multitude.
"For whatever we lose (like a you or a me)
It's always ourselves we find in the sea."
-e.e. cummings