Leyline of Chaos

If Leyline of Chaos is in your opening hand, you may begin the game with it on the battlefield.
As you cast spells with converted mana cost 3 or greater during your turn, they gain cascade and "When you cast this spell, flip a coin. If you lose the flip, counter all spells." (When you cast the spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom of your library in a random orde