you stall as hard as you can with the other zombies til you get an Undead Alchemist out on the field then mill them while you gain all the life ever
---The Zerg---
Hex Parasite This little bastard will remove the +1 +1 on the undying zombies so they cant be killed
Gravecrawler: usually turns up in the opening hand 2 to 4 quick damage in the first 2 turns. also forces enemy into defense mode
Butcher Ghoul: 2 cmc undying zombie. Great blocker
Geralf's Messenger: 2 damage when he enters the battlefield and when he dies, he comes back even bigger (4/3) while dealing another round of direct damage.
Unbreathing Horde: relatively cheap, great blockers (remove a counter instead of being dealt damage), and since It runs a lot of zombies they sometimes comes on the board as 8/8 creature.
---Buffs--
Diregraf Captain: buffs your zombies with +1+1 Deathtouch & does extra dmg when a zombie dies
Mikaeus, the Unhallowed: Gives all your other zombies creatures undying & +1/+1 (including the tokens)
---The Combo Burn---
Undead Alchemist: The most evil card ever
Consuming Aberration: save this for once you have milled the enemy some, this can stop any big cards that happen to show up
Rogue's Passage: This ability is a bit coslty, but when used with Undead Alchemist on the board it almost guarantees you to create new Zombie tokens.
---Dirty Tricks---
Jar of Eyeballs: because the idea of this deck is based around use a zombie to block, let it die, then come back stronger makes this card extremely powerful especially when you are removing +1+1 counters to keep them undying
Endless Ranks of the Dead: allows zombies to multiply like rabbits
Retribution of the Ancients: this card is so dirty because of how it can be used to destroy your own zombies for the +1+1 or destroy a problem on the field. because the +1+1 counters do not return at the end of turn this makes it easier to keep your zombies undying
Fate Transfer: because its an instant you can remove the counters from a zombie blocking [with undying counters] allowing him to block, die, then come back from the dead with +1+1. while boosting another zombie [make sure you have a way to remove these counters later or that zombie wont be coming back