Mega Heal Bomb is an alternate ability of the Scientist's Sticky Explody Ball, but it does not hurt plants. It will explode after 3.5 seconds while being deployed. When it explodes, it will heal all zombies in its radius by 50 health. After that, it takes for 15 seconds to recharge.
The Mega Heal Bomb is always popular at parties. Just roll it into a group of friends and watch their health replenish before your eyes!
The Mega Heal Bomb is good for three things; first, it is good for patching up groups of zombies that have all gotten a little banged up, second, it is good for giving singular zombies a quick health boost instead of deploying the Zombie Heal Station (and then being forced to wait for 45 seconds for it to become usable again), and finally, the Mega Heal Bomb is also good for personal healing when far away from others (this allows you to save the Zombie Heal Station for your teammates).
Do not be afraid to deploy the Mega Heal Bomb near groups of injured zombies, if they see it coming, it should attract everyone who wants healing.