I do NOT understand Bone Shield

[Delmuir]

I hit a bone shield with one charge like five times and have minions hitting it and it never goes down. I know it recovers quickly but what the hell? Sometimes it also has a damage shield so... does the damage shield have priority?!? Why didn't it go down before?

I legitimately don't understand it. Sometimes it goes down without a problem but other times, it's impenetrable and eternal. Is it working properly?!? My experiences with it seem completely arbitrary.

And yes, I understand that shutting it down is ideal but it's not always an option.

[whitelion]

Some enemies on high difficulty have very high level of bone shield so they get a new charge every 1-2 turns and have high max charges. It's basically impossible to kill weirdling on insane of you can't output multiple significant sources of damage per turn (or strip bone shield.)

[Delmuir]

Solid point but this was on NORMAL...

I killed him anyway but it took way longer than made sense. I keep running into problems with Bone Shield...