Board Thread:Plants vs. Zombies 2: It's About Time/@comment-25154254-20150403114523/@comment-25912702-20150403234225

Maybe there's going to be sun tiles. You should only plant sun producers on these tiles since at random times during the waves of zombies, they're struck by intense beams of sunlight! Zombies and normal plants are both destroyed but sun producers, when hit, create some extra sun.

Another idea is shifty columns. During the waves of zombies an column may randomly move one tile up or down. This can end up killing plants as well as zombies. Maybe column pod is a plant that holds the column down so it doesn't move?