Imposter is an eventzombiecard in Plants vs. Zombies Heroes and a member of the Sneaky class. He costs 1 to play and has 2/1. He doesn't have any traits, and his ability Conjures an Imp card that costs 1, including another Imposter, when he is destroyed, then places a mustache on that Imp when it is played. The Conjured Imp also belongs in the mustache tribe, although it does not say that in its tribes and only says "Conjured by Imposter - Gained a Mustache." instead.
Getting an Imp is the worst case scenario, as it does almost nothing, only serving as a meat shield or as a glass cannon if paired with Toxic Waste Imp or as extra cards with Imp Commander. However, all the other options you can get are decent early-game plays. Mini-Ninja has the Anti-Hero trait, meaning he can do some good damage early in the match. Impfinity Clone is fragile, but it can act as a Snorkel Zombie with the Imp and its given Mustache tribe. Loose Cannon can do guaranteed damage to your opponent before attacking. Leprechaun Imp has decent stats and will shuffle a Pot of Gold into your deck, which is helpful if you are using an Imp deck. Neutron Imp works wonders if your deck has lots of environments in it. And finally, getting another Imposter will allow you to Conjure another Imp.
Having no traits or extraordinarily good stats for a 1-brain card, Impostor himself isn't much of a threat. However, you will want to watch out for Impostor's "when destroyed" ability; while the Imps may cost only 1 brain, they can cause you a bit of trouble early on if unprepared, especially with Imp Commander or Toxic Waste Imp.
Damaging abilities like Banana Bomb's and Berry Blast's are the most simple and universal answer to both Impostor and the Imp Conjured, but most attacking plants can also deal with them with little trouble. However, make sure to remove any Toxic Waste Imps first if you want to use any high-health plants, as the Imps will be Deadly.
Impostor is the only card to affect other cards' tribes and cosmetically change other cards' appearances.
When an Imposter is Conjured by Imposter, it doesn't gain a mustache due to already having one.
When Plants vs. Zombies Heroes was first released, if the player carefully looked at the crowd of zombies in the Multiplayer, they could see Imposter, despite him being released many updates after the release of the game.
Imposter's textures have also been in the game's soft-launch, suggesting it was already in the game files before its official release.