Endless Ranks of the Dead

Oracle Text

At the beginning of your upkeep, create X 2/2 black Zombie creature tokens, where X is half the number of Zombies you control, rounded down.

Card Rulings

9/22/2011 If you control fewer than two Zombies, you won’t get any tokens.
9/22/2011 The number of Zombies you control is counted when the ability resolves. If you control multiple Endless Ranks of the Dead, the tokens you get when the first ability resolves will count for the subsequent abilities (if the tokens are still under your control at that time).