I say Biz comes back as her namesake: a ghost. She could have most of her usual abilities/powers and then be working on her ghostly abilities: cause fear, walking through walls, invisibility, etc. Those could level up as a ghost might.
I say she comes back like this:
Ghost
Requirements: dead
Prime Req: same as in life
HD: same as in life. Character returns with same HP
Max Level: 10
Armor: None
Weapons: special*
Languages: same as in life
Ghosts are the returned versions of PCs. They retain the spells and abilities they had on death, however they advance from now on as a ghost. They remain with the party they died a part of and it is through their faith and love that it persists.
Ghosts cannot don armor nor can they use weapons. They have instead intangibility and
cause fear.
- Intangibility: Character gains ability to have weapons pass through with no harm starting at 7[12] and descending[ascending] by one every two levels (so AC 7[12] at levels 1 and 2, AC 6[13] at 3 and 4, etc.
- Case fear: as per spell. Must make a to-hit. At level one this is a hand-to-hand attack. At level 3 it is ranged but only one character attacked per round. At level 6 it can affect 1d6 HD enemies in a ranged attack, at level 8 2d6 HD enemies, and at level 10 3d6 HD enemies. Starting at 5th level, cause fear also causes 1d4HP damage per ghostly level as fear can be a serious shock to the system.
XP advances as cleric. Saving Throws as cleric. HP as MU. To hit as thief.
Ghosts cannot use potions or other magic items.
When a ghost hits 0 hit points, it "fades" and cannot act until it is reconstituted by the love of its companions (aka, once combat is over). A ghost takes hits as per usual: normal weapons doing half-damage and magic weapons acting as usual.
At third level, a ghost can become
invisible. Invisibility lasts # of rounds as ghostly level. Attacking resets invisibility.
At fifth level, a ghost can heal wounds as per
cure light wounds. Every two level adds d6+1 to heal.
At seventh level, a ghost can invade dreams of the living. If a living person is asleep, the ghost can invade the dream and hopefully gain insight, knowledge, or that person's plans. Chance to gain insight: 30% chance at 7th level. 45% at 8th level. 60% at 9th level. 75% at 10th level.
At tenth level, a ghost can be done and go on to the afterlife. A ghost in the afterlife can return to help companions but cannot advance.
Just something I threw together: the DM could of course change as needed. I'd love to see Connivingsumo or anyone else play this.