Adipose Offspring (Surge Foil) [Doctor Who]

Emerge {5}{W} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.)
When Adipose Offspring enters the battlefield, create a 2/2 white Alien creature token. If Adipose Offspring's emerge cost was paid, instead create X of those tokens, where X is the sacrificed creature's toughness.