Stone of the Gods

When Stone of the Gods enters the battlefield, if
you have five or more cards on the battlefield, all
creatures you control have +1/+1 and Stone of
the Gods gets +X/+X, where X is equal to the
number of creatures you control.
Whenever a creature you control attacks, Stone
of the Gods gets +Y/+0 until end of turn, where
Y is equal to the amount of damage delt by that
creature.