its Yawgmoth's Will for zombies, if you can do anything with that
It's a game-ender, typically sweeping away your opponent's entire board, while preserving any colorless permanents you've chosen to play, and, more often than not, also leaving Ugin alive to keep pecking away with their +2 damage-dealing power
For two mana you can choose to activate one of its effects, choosing between gaining life, dealing damage to flying creatures, putting a +1/+1 token on a creature, or bringing cards out of your graveyard to put them back into your library
Szarekh ensures that your graveyard is more than just a resting place, its a staging ground for your armys resurgence
However, it's actually a ticking time bomb that would unleash a monstrous indestructible creature
You can play Unholy Annex early for card advantage and potentially unlock Ritual Chamber later for a big threat