Inner Destruction Bug

Inner Destruction didn’t interact well with additional casting abilities. Whenever my Evoker-Occultist Team come along an enemy with Inner Destruction, each of my creatures cast it without an end until they’re all dead.

This seems less like a bug, and more like your traits functioning as they should. Inner Destruction is counted as a spell that your creatures are casting, so it makes sense that any multi-cast trait or perk would apply.