"Shambling Undead" from "The Broken Elegy" not working properly with "The Dark Monarch"

Bug Report ID: #124.505.681
Bug Report ID: #3.424.185.522

While having "The Broken Elegy Foul Staff" and any variation of "The Dark Monarch Lich's Circlet" equipped, the staff will consume a corpse on the ground, but not summon a minion.

If you then have a "Heartbound Loop Moonstone Ring" ring equipped, you will take damage from the consumption of the corpse from the staff, as if the Shambling Undead minion is being killed.

Not only that, but the amount of Rotten Bulwark given by the staff is lower with the Dark Monarch equipped as it would be without the helmet. This implies that, somehow, the maximum life of the minion is being lowered.

Necessary components for reproducing the bug:
"The Broken Elegy Foul Staff"
Any "The Dark Monarch Lich's Circlet"
"Heartbound Loop Moonstone Ring"
Desecrate (Lvl 1) + Cast When Damage Taken support (Lvl 1)
Another Desecrate (Lvl 1)

Steps to reproduce:
Cast Desecrate and wait