Crusader

The Crusader is the first tank enemy of Black Citadel, boasting a much higher HP than that of BBBs along with damage. Being undead Zards brought back to life, upon dying, they will release their gas to heal nearby enemies for several seconds. This proves troublesome especially when multiple Crusaders die at once, giving those affected ungodly regeneration.

They're an easy target to knock backwards due to their slow speed, but groups of crusaders are a problem, as a Crusader can hit a building through another Crusader! This results in Robo Bully being easily overwhelmed unless you have good AoE towers and/or knockback. Good buildings against the Crusader are: BETTY, Grappler, Bunker, and Discharger.

Notably, Hyperknights can get stuck behind Crusaders due to their weight and size, which helps due to the Hyperknight's normally fast speed.