Help understand Div Scarab of Plenty

Can someone explain this scarab to me? 800% increased chance to drop divination cards, but in my experience (20+ uses), it drops 0 divination cards, and spawns purple monsters that arent targetable / killable. I dont understand what to do, when purple mobs spawn am I just supposed to run off screen until their timer ends? Am I supposed to be able to target them? Why do they not drop divination cards. Help!

If You have like 0.001% to drop then multiplying it by 800 does litte to nothing.