Wilhelt, the Rotcleaver

Whenever another Zombie you control dies, if it didn't have decayed, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
At the beginning of your end step, you may sacrifice a Zombie. If you do, draw a card.

Unraveling Mummy

{1}{W}: Target attacking Zombie gains lifelink until end of turn.
{1}{B}: Target attacking Zombie gains deathtouch until end of turn.

In Oketra's Name

Zombies you control get +2/+1 until end of turn. Other creatures you control get +1/+1 until end of turn.

Unconventional Tactics

Target creature gets +3/+3 and gains flying until end of turn.
Whenever a Zombie you control enters, you may pay {W}. If you do, return Unconventional Tactics from your graveyard to your hand.

Corpse Knight

Whenever another creature you control enters, each opponent loses 1 life.

Wayward Servant

Whenever another Zombie you control enters, each opponent loses 1 life and you gain 1 life.

Binding Mummy

Whenever another Zombie you control enters, you may tap target artifact or creature.

Time to Reflect

Exile target creature that blocked or was blocked by a Zombie this turn.

Varina, Lich Queen

Whenever you attack with one or more Zombies, draw that many cards, then discard that many cards. You gain that much life.
{2}, Exile two cards from your graveyard: Create a tapped 2/2 black Zombie creature token.

God-Eternal Oketra

Double strike
Whenever you cast a creature spell, create a 4/4 black Zombie Warrior creature token with vigilance.
When God-Eternal Oketra dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Necromancer's Covenant

When Necromancer's Covenant enters, exile all creature cards from target player's graveyard, then create a 2/2 black Zombie creature token for each card exiled this way.
Zombies you control have lifelink.

Nevinyrral, Urborg Tyrant

Hexproof from artifacts, creatures, and enchantments
When Nevinyrral, Urborg Tyrant enters, create a tapped 2/2 black Zombie creature token for each creature that died this turn.
When Nevinyrral dies, you may pay {1}. When you do, destroy all artifacts, creatures, and enchantments.