Monolith of the Colossal

Monolith of the Colossal costs {5} less to cast
and cant be countered if you control a creature with power 8 or greater.
Creature spells you cast cost {x} less to cast where X is the greatest power amongst creatures you control.
{3}{g}{g}{g}: Creatures you control get +1/+1, trample and indestructible until end of turn.