Staff of Cherished Necromancy build? No inflict wounds since it's once per long rest.

[Accel Lex]

I don't like relying on once per short/long rest resources, so I like using melee, ranged, cantrips, or a resource that has a lot of value. Haste for example is worth it since it lets my best characters do more for 10 turns. A damage spell doesn't always provide me the same value, or can be replaced with an arrow type or scroll I have.
The Staff would let my stingy self use spells more often.

I'm planning on giving it to Shadowheart. My main is a monk, Lae'zel is a self sustain barbarian, hireling draugr is a pickpocket.

Shadowheart would usually just stand there. Sanctuary if I cast Haste with an item. Or used summons. She missed most of her shots. I heard Sorcerer has haste as a spell, so I gave her that class just to be able to cast it. I tried multi classing her with a few other things like Bard, and she actually lands her shots now. Dragon Sorcerer with Ice as main cantrip and a ring that makes a ice surface is my main for her, or giving her Eldritch Blast.
I'd like to know what's recommended to build for the Staff.
I like having Haste as a just in case/fun ability, Sanctuary as well to be safe while using it but not necessary, ice cantrip or eldritch blast for damage I think to charge the staff.