Sandstorms, Camel Zombies, Pharaoh Zombies, and high concentration of zombie hordes contribute to the difficulty of this level. Mainly, the newly discovered Pharaoh Zombie. This zombie has a high amount of health, and once the casket is broken, the zombie within comes storming out with a fast speed. This zombie acts similarly to Newspaper Zombie, but with more health. Camel Zombies arrive in humps of more than three while Pharaoh Zombies will back themselves up by blending with the sandstorms or their allies. Instant-use plants are recommended to deal with the Camel Zombies and Pharaoh Zombies. However, an instant will only break the casket, letting the zombie free without harm. Chomper or Toadstool (if the player bought them), can instantly kill them.
The small number next to the zombie icon means that zombie will always appear in that lane, with 1 being the topmost lane and 5 being the bottommost one.
To deal with Pharaoh Zombies, use Potato Mines or Bloomerang's Plant Food ability. One thing you need to know is that Pharaoh Zombies needs two instant-kill plants to be killed, since the sarcophagus absorbs extra damage from projectiles.