i think the growing entity is not OP. twice the cost of a normal growth skill.
and regarding the shrinking entity, it is way too powerful,
maybe this way.
10|10 is the starting stats.
then per turn it loses 2 attack stats and 3 or 2 hp stats.
10 + 8 +6 +4 = 28, still a fair damage plus the gaining of quantas.
10 + 8 + 6 + 4 + 2 = 30. more than the 28 damage by 2.
assuming it is not targeted by any damaging skill.
also increase the to-cast cost of the shrinking entity. for it also generates like a quantum pillar per turn less one.
ceteris paribus