Yardu, Voracious Alchemist

Whenever you spent 4 or more red mana
to cast a spell, create a token,
with is a nonlegendary copy of Yardu, Voracious Alchemist.
{10}: Destroy all creatures and planeswakers your opponent controls.
You can sascrifiste X copies of Yardu, Voracious Alchemist,
to pay for that ability X mana less.