Portal Combat

Portal Combat is a Night mini-game without graves. Instead, there are two pairs of connected portals, which zombies and projectiles will be able to pass through. It is also a Conveyor-Belt Level.

Strategies
The player should be careful of the portals, but not base their entire defense around them, as they will frequently shift positions. It is a good idea to get a Cactus in every lane as fast as possible, although it is a good idea to save up at least one in the Conveyor Belt, in case a Balloon Zombie comes where there is not anything to stop it. Another good idea is to save up the Cherry Bombs whenever they appear and only use them when you have to (e.g. on Football Zombies, or if a Portal appears in the back, behind most of the player's plants). Use Torchwoods wisely, as they do not work on Cacti, and place Wall-nuts in front of particularly vulnerable Portals. If a portal is too close to the left end of the lawn, try planting Wall-nuts or any other defensive plants to stop the Zombies from entering the house.

Trivia

 * Occasionally, portals may appear in positions where, with the same set of portals in a single row, zombies may not be able to walk on a few squares and any projectiles that were fired (or less likely, zombies) before the portals switched may be trapped in an endless circuit, until the portals move away.
 * The name "Portal Combat" is a pun based on the video game series Mortal Kombat. The white circular portal is a reference to the latter game series.
 * The achievement No Fungus Among Us cannot be unlocked in this level, most likely because all of the plants available in this minigame are not mushrooms.
 * When a Lawn Mower heads towards a portal, it will teleport to the other portal.
 * Portals will teleport all projectiles, even high spikes which look like they will pass over the portals.
 * If a Cherry Bomb is planted horizontally adjacent to a portal, there is an occasional glitch where the explosion will go through the portal. If this glitch occurrs, the explosion radius will follow the normal rules for passing through portals, but only on the square directly next to the other portal.
 * Along with Zombiquarium and Beghouled Twist, this mini-game is in a Mini-game pack to buy instead of being in the normal mini-game section in the iPad version.