Just like with Adaptive Automaton, its also a nice addition to the likes of Ayula, Queen Among Bears or Magda, Brazen Outlaw, where creature buffs are few and far between
Next come two obvious questions
We aren't going to have a terrible ending here in Evilquestria though
At one of the latter stages of casting spells a player defines its total cost: Total cost is a spells mana cost or alternative cost, plus all additional costs, plus all effects that increase mana cost, minus all effects that decrease mana cost
Mirror EntityMirror Entity, as referenced above, can activate its ability for X = 0 for an over-easy Mass PolymorphMass Polymorph for your board
If you sacrifice a creature with a mana cost of two, you can grab a creature with a mana cost of up to four