Venax, Primal Calamity

Perplex (If you reveal this card from your library when you cascade, exile it. You may cast this card without paying the colored portion of its mana cost.)
The first spell you cast each turn gains cascade, cascade.
As long as you've cascaded this turn, Venax, Primal Calamity gains flying and annihilator 3.
"As your plane dies, take comfort in knowing that it serves a higher purpose; my completion."