Dread Slaver + Flayer of the Hatebound + Mikaeus, the Unhallowed + Phyrexian Altar

Dread Slaver

Flayer of the Hatebound

Mikaeus, the Unhallowed

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing Dread Slaver, adding one mana of any color.
2. When Dread Slaver dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. When Dread Slaver enters the battlefield, Flayer of the Hatebound triggers, causing Dread Slaver to deal damage to itself equal to its power.
4. Activate Phyrexian Altar by sacrificing Dread Slaver, adding one mana of any color.
5. Dread Slaver triggers, returning itself from your graveyard to the battlefield.
6. Repeat from step 3.

This clever loop is held together by Mikaeus, the Unhallowed, whose static ability grants undying to all your non-Human creatures, turning any graveyard trip into an immediate return with a +1/+1 counter. When you sacrifice Dread Slaver to Phyrexian Altar for mana, Flayer of the Hatebound makes sure its return from the graveyard triggers damage directly to itself—resetting its health and sending it right back to the yard. Because the damage dealt by Flayer of the Hatebound comes from Dread Slaver itself, Dread Slaver's own replacement effect triggers to steal it back as a Zombie if needed, while Mikaeus keeps the undying engine cycling endlessly to fuel infinite mana and damage.