The River of Long Knives

As long as your life total is greater than or equal to half your starting life total, The River of Long Knives does not untap during your untap step.

{t}: Add {b}.

Delirium —{b}, Pay 2 life: Exile target creature card from
a graveyard. Create a 2/2 black Zombie creature token. Activate only if there are four or more card types among cards in your graveyard and only as a sorcery.