Chompzilla enjoys eating Zombies whole. She does not enjoy the indigestion that follows.
Strategies
With
In the early turns, this trick is useful at destroying glass cannons like Mini-Ninja or Tennis Champ without sacrificing a plant. And in the late-game, it gains much more potential since you can destroy even Gargantuars at a very cheap cost, provided they have the lowest health. However, this trick has trouble destroying threats with high health like Template:PvZHLink or Jester if there are other zombies with lower health on the field. If there are powerful zombies on the field, and weak zombies on the field, try getting rid of the weak zombies so you can easily destroy the powerful zombie. Instant-kill tricks help, so in this scenario, use those first if you only have 6 sun or less.
Against
The best way to counter this trick is to make sure there is always another zombie with lower health on the field to prevent the key zombie from becoming the target. If the health of a powerful zombie gets very low, heal it with Medic or any health-boosting trick so it gets out of range of being destroyed by Devour.
The single player AI will almost always use this instantly, so it can give you an advantage if you use a weak zombie.