Geist Ult hasn't been able to proc Mystic Reverb ever since they changed the damage type from spirit to true damage. Unsure whether or not this was intentional or not, regardless you can still imbue Reverb onto it.
Lady Geist's ult does not trigger mystic reverb even though the item can be imbued on it. This is a new bug as the combo has worked for over a year at this point before now.
