Crazed, the Enchancer

{r/g}, {t}: The next creature spell you cast this turn
has non-Goblin Offering (You may cast that card
any time you could cast an instant by sacrificing a
non-Goblin and paying the difference in mana costs
between that and the sacrificed non-Goblin. Mana
cost includes color.)
If you cast a Goblin creature spell as a result of
the offering, that creature gains +X/+X until
end of turn where X is equal to the sacrificed
creature's power.