Zephya, the Mounters Sin

{1}{b}{b}{b}: Create a token that a copy of target Horse, Unicorn, or Dualicorn in your graveyard except it gets -2/-1 and has haste
{t}: Sacrifice Zephya, the Mounters Sin and any amount of other creatures then destroy x permanents where x is the amount of creatures sacrificed in this way. Then create and {x}/{x} unicorn avatar named The Darkest Night onto the battlefield. It has Infect, Flying, and Mount{1}{b}{b}.