Ghouls' Night Out by paying ({3} magic symbol) ({B} magic symbol) ({B} magic symbol) , returning
Eternal Witness from your graveyard to the battlefield, and at least two other creatures from your opponents' graveyards to the battlefield under your control.
When
Eternal Witness enters the battlefield, it triggers, returning
Ghouls' Night Out from your graveyard to your hand.
Activate
Phyrexian Altar three times by sacrificing
Eternal Witness and the two creatures your opponents own, adding ({1} magic symbol) ({B} magic symbol) ({B} magic symbol) .
When the three creatures die,
Headless Rider triggers three times, creating three 2/2 Zombie creature tokens.
Activate
Phyrexian Altar twice by sacrificing two Zombies, adding ({2} magic symbol) .