!Damaged irongolem with a healthbar
MobHealthBars is a plugin that adds healthbars to your server without interfering with the mob's name, and without revealing mobs that players can't otherwise see.
The healthbar is a separate entity that only appears when a player looks directly at a mob, and it disapears 5 seconds later (if a mob goes 5 seconds without being directly looked at by a player, the healthbar disapears).
The healthbar changes color based on the percentage of health that is remaining.
The healthbar used to be a TextDisplay entity, but for some reason TextDisplays collide with projectiles, so healthbars were switched to being invisible armorstands (which don't collide with projectiles thanks to the marker tag).