Fae such as the one Bellatrix had disturbed were more akin to minor deities than anything remotely mortal, and the ones who had been fed -  ritualistically, over a period of many years and then given a   reason to use their power  - were the strongest of the lot. However long it had been since the Muggles had taken over that property was not long enough to dull Hermione’s power and magnificence. Bellatrix was -  against her better judgement  - relishing in the knowledge that Hermione was here for her.