Guides:Claw for Grasp, Bite for Threes
From The Urban Dead Wiki
Zombie Tactics 
The information on this page or section discusses a zombie strategy. 
The simple mnemonic of "Claw for Grasp, Bite for Threes" encapsulates the zombie attack routine that results in the maximum number of survivor deaths for the fewest AP expended by zombies.
Important Update
The mnemonic above doesn't quite cover it. The best, most AP efficient zombie attack strategy is as follows:
 If the target is at a HP that is an exact multiple of 3 or a multiple of 3 +2, then claws only are the best option.
 If the target is at a HP that is a multiple of 3 +1, attack with claws until a grab is engaged. Then, attempt to bite until either a bite lands, or the grip is broken. If the grip breaks, go back to claws. If a bite lands (taking them to an exact multiple of 3), go back to claws.
 The exception to this tactic is if the target is at exactly 4HP; in this instance, it is always better to bite.
These points make the below text obsolete, though the stats in the tables are correct. More stats are on the talk page, courtesy of Mortificant. David Suzuki 11:46, 14 August 2008 (BST)
Claw for Grasp
In most cases, you want to use claw attacks to establish a grasp. There are a few exceptions and things to keep in mind, however. One thing to keep in mind is that only one zombie can have a grasp on a survivor at a time. For this reason, Zombies who attack in large groups should try to each pick their own target, rather than "mobbing up" on a single target. Another is that, even without a grasp bonus, bite attacks alone are the fastest way to kill a survivor who has exactly 4 or 8 HP.
Bite For Threes
If a survivors HP total is NOT a multiple of three, and you have established a grasp, you should be making a bite attack in an attempt to get them to a multiple of three. In fact, even if you do not have a grasp, bite attacks are better when the survivor has exactly 4 or 8 HP; "biting for threes" is simply a way of chipping off that 4 or 8 HP while you still have a tangling grasp bonus.
For evidence of the effectiveness of bites vs 4 or 8 HPs, see the charts below. Note that these charts assume the tangling grasp is always in effect for claws, and never for bites thus, the bite attack is potentially better than the charts indicate, and claws are actually somewhat worse than indicated. Figures are as calculated to full precision and then rounded; if you are good at this sort of thing, please extend the chart and explain your method on the talk page.

