[LDiCesare]

I tested them again, and my conclusion is:
Grendelkin are worthless.
Yes, worthless. A waste of gems.
For hardly more gems, I can get a sea troll king with his retinue. He's able to pack some punch underwater. Grendelkin underwater suck. Why do they cost that many WATER gems then?
They're a waste of gems. I'd rather use water gems to summon stuff that can be used underwater.
Either give them amphibious or make them require anything but water gems to summon.
Right now I have found in my MP game 2 units to be better than grendelkin: Bane lords (yes, seriously) and sea troll kings.