Immorticia is a zombie hero in Plants vs. Zombies Heroes. She relies heavily on tricks for her play style. She leads the Brainy and Beastly types. Her signature superpower trick is Witch's Familiar. It summons a card called Zom-Bats in the lane of her choice. When it hurts a plant, she draws a card.
Her design is based on a typical Halloween witch, although her hair resembles that of Frankenstein's bride. She also seems to have some inspiration from Dracula.
Immorticia's name is a portmanteau of "immortal", referring to the fact that this zombie cannot be destroyed but can be knocked out and "morticia", referring to the Addam's family character named Morticia Addams.
Statistics
Classes: Brainy, Beastly
Superpowers:
Signature:Witch's Familiar: Summons a Zom-Bats in a lane of Immorticia's choice that makes Immorticia draw a card when it deals damage to a plant.
Yes, she's a Zombie AND a witch. She believes death is too short to limit oneself.
Strategies
With
Immorticia has a complicated class combination of Brainy and Beastly zombies. This means she has access to both bonus attack and extremely strong buffing tricks.
Immorticia has the potential to allow select zombies to last longer than normal on the battlefield, and consequently deal more damage to the enemy hero. A huge examples are the Paparazzi Zombie, which has the greatest synergy with Vitamin Z. Playing Vitamin Z on Paparazzi gives it a massive +4/+4 for 3 brains. Gentleman Zombie is also a teammate worth keeping alive for as long as possible. This will allow Immorticia to play more expensive cards earlier.
As stated by Crazy Dave, Immorticia's classes give her amazing Gargantuar synergy. Her Brainy class gives her access to Wizard Gargantuar, while her Beastly class allows her to use Nurse Gargantuar, Deep Sea Gargantuar, and Smashing Gargantuar. Wizard gives all Gargantuars Bullseye, while Smashing Gargantuar gives all Gargantuars Frenzy. These two make both Nurse and Deep Sea Gargantuar incredible threats. Deep Sea will attack from a mostly unprotected lane with Bullseye, while Nurse's Frenzied bonus attacks will heal Immorticia for each plant destroyed.
However, Immorticia's main drawback is her vast trick disposal. Having tons of tricks is great for a deck, but can also impact it a lot. Fewer zombies can be really bad for a hand, especially starting a match. Immorticia decks should not try and put every single trick in, as it will clog the deck and likely make a poor deck. However, Haunting Zombie can solve this a bit, as it is a good early game tool to have with decks with minimal zombies.
Against
Immorticia must be dealt with as early as possible. Beastly heroes need a few turns to truly begin boosting. Her Brainy class helps her do this earlier than others, provided that her important brain-granting zombies survive.
One method is to adapt to her powerful bag of tricks. Distributing buffs evenly between a large number of plants on the board will minimize the value of Locust Swarm and Rocket Science. Putting too many boosts on a single plant makes it a target for the above mentioned tricks. Rushing Immorticia with cheap, high-attack plants such as mushrooms to deal heavy damage is an example of this method.
Another option is to duplicate her play style as closely as possible. Buffing or healing plants while preventing zombies from being buffed and removing heavily buffed zombies is effective, although the match may be in stalemate for a long time. Outsmarting her with your own tricks is also an option, although non-Smarty heroes may find this method problematic.
Gallery
Plants vs. Zombies Wiki has a gallery for Immorticia.
Brainy and 
Beastly types. Her signature superpower trick is Witch's Familiar. It summons a card called Zom-Bats in the lane of her choice. When it hurts a plant, she draws a card.
Smarty heroes may find this method problematic.
Brainy
Crazy
Hearty
Sneaky