B2 Super Battle Droids are heavy droids equipped with a wrist blaster and wrist rockets. The Droid will target infantry forces and melee them in close proximity. The Droid is extremely durable to explosives which have little effect, and although they are equipped with tough armor plating have to be taken down with small arms fire.
The GAR has developed "Droid Poppers" which are extremely effective against B2's.
Once a  B2 has been destroyed, there may be a chance that it gets back up.