Tamsa, Master of the School

Submerge (You may have this creature enter the
battlefield with a -1/-1 counter on it. If you do, it
becomes submerged and it can't be blocked.)
Tamsa, Master of the School gets +1/+1 for each creature you control.
{w}{u}, Tap two untapped creatures you control:
Tamsa gains hexproof until end of turn.