Basically, it's just to prepare for Flood as it is right now. I was thinking of adding slight damage about equivalent to Thunderstorm, but the damage only affecting the non-water, non-other creatures. Using it prior to or while having Flood on the field would also help for you to free the middle row to cover it with some Malignant cells on your opponent's side of the field and yours so you can maybe summon non-water creatures.
But, yes, it is one dimensional in the sense as I was going for Flood preparation.
Would it be too overpowered if it was a
permanent permanent with an upkeep cost, while dealing damage to the middle row at the end of each turn while scattering the creatures to the top and bottom rows?
Editedit: I intentionally didn't fix the water mark, because I knew it had some kinks to work out, I was just waiting for feedback.