So discovered a frustrating bug on harrow that can prevent you from damaging him and keep him immune. First found you can have a longer damage phase if you can make him damage himself (whether big shocky barrels or trap doors). But this can also bug him out where if you happen to time it just right where he’ll get his shield back and he hurts himself at the same time, no matter what you do after you take the shield down he’s now permanently immune for the whole fight and won’t regain his shield either. He just stays immune. No matter how many times you do the mechanics to start DPS he’ll stay immune even with no shields.