I assume you mean the Staff of Souls, which enters the game as a promotion of Barbatos the Lich.
It seems more like something for an arcane unit to me (and It is much more potent in my version.

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(I actually just changed it so that the Lichdom Spell is no longer allowed by Death III Sorcery, and it no longer has a limited amount of liches you can have. Instead it requires that the unit have channeling II, be either an arcane unit or a Vampire Lord, and either have this item or be standing in the Broken Sepulcher.
I made a new Death III Sorcery spell that creates a new Accursed Ground feature. A living unit killed on a tile with this improvement tile is resurrected as a Skeleton of equal strength and all its promotions except channeling 1/2/3, blessed, divine, sorcery, summoning, valor, or morale, but also injured, having the enraged promotion, and belonging to the barbarian state (I made Mokka's Cauldron work the same way, except for the enraged and barbarian part. ) Like fallout, this causes negative yields (but only -1, not -3 like fallout) can be removed by the sanctify spell (which I made Good aligned AI's now do even in rival territory. Kael's coding only let AIs sanctify in their own lands.) Of course, casting the Curse the Ground spell causes war.
Then I added another spell requiring the Staff of Souls and Channeling III:
Necromastery. This spell converts all undead units within a two tile range to the caster's control, except for units that also have channeling III.
Since I figured I was on a roll, I also changed Hyborem's trident equipment (Gela) to provide 2 Entropy Affinity instead of +2 unholy damage, and to allow a similar spell (also requiring its possessor have heroic strength 2 and your state religion be AV):
Dynamis Agares ("The Power/Authority of Agares," in Greek), which allows its wielder to take control of
any demon. I can't wait to play a game where I go CoE, send CoE recon units steal this equipment, give it my hero, convert to AV, then convert Hyborem himself to my side, along wtith most of his army, the 4 horsemen, and the Avatar of Wrath. Exploit you say? What Exploit?

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