ToME: the Tales of Maj'Eyal

1. Is Channel Staff and Staff Mastery useful for Necromancer spells
2. Considering the negatives, is it still net beneficial for an ogre necromancer to also be able to use a shield?

1. Most classes don't really have use for the staff tree even if they use a staff. You should have enough spells to use to not need them at all. Feel free to get the tree if you want defensive posture and can spare the points.
2. From what I remember, the negatives for ogre wielding aren't as bad as they appear due to how powers scale, and you don't do melee hits so proc dmg is not an issue. You can basically turn any staff into a shortstaff with a bit of a nerf to your stats (which can also be mitigated with size+ gear).