Etrfog

Etrfog is an instant-use plant, which blinds zombies ahead of it.

Overview
When Etrfog is planted, it opens its mouth, releases a dark cloud, and then disappears. This cloud, which extends 4 tiles ahead of it, makes zombies unable to eat or attack any plant. Instead, they walk right past them, unless it's a Tall-nut or some other heavy-duty defense plant. This cloud lingers for 5 seconds, and then dissipates.

Etrfog is based off of the etrog, and its name is a portmanteau of "etrog" and "fog."