Yeah, the items included work fine but specifically The Shell and the Tuff Twins (both bosses that need to be hit with explosives to damage properly) were causing an error, "PreEntityTakeDamageFailed: c stack overflow" for me. It wasn't related to any particular items. Once I disable just this mod, those two bosses work fine. Hope you can figure out a fix for that.

Some of the items don't play nice in multiplayer, but nothing should be changed if you don't have any of the items in this mod.

I had none, happened twice while playing multiplayer. Against the main boss and a random greed miniboss. The wackiest mod I had was "Boss butch"

I'll look into it. Do you remember which item(s) you had?

Makes bosses unkillable for some reason...

So, any chance to know what's inside before downloading?

Can't wait to try Pebble Top.