Some thoughts:
-Staves function as a skill on a stick rather than a martial weapon so the base damage won't scale according to your attribute - unfortunately having 16 spawning won't give you an extra ~15% damage.
-The wiki claims the attribute only affects critical chance for martial weapons. The formula isn't clear to me so I ran six three minute trials against the master of damage with 9 and 16 fire magic, with the following total damage results:
9: 1707, 1660, 1675, 1670, 1680, 1689 (average 1680.16)
16: 1733, 1690, 1728, 1660, 1771, 1691 (average 1712.16)
If the crit chance is supposedly the same, why is there a discrepancy in damage? I would think the sample size is big enough here. I suppose if you look at it from a dps point of view an extra 32 points over 180 seconds is next to nothing, but the 9 scores look too consistent to ever reach 1730+ without an absurd amount of luck. Idk. Fortunately, it doesn't really matter if we understand it or not because we'll be maxing spawning regardless.
-Great Dwarf Weapon would be great, but cannot self target. It would also remove the need to invest into channeling (but add the need to consume alcohol), allowing you to either max out the conjure attribute (+3 damage) or spend elsewhere.
-SS+Conjure+EBSoH+GDW+IATS = 109 damage. A customised 15^50 staff crit would deal 43 damage against a 60AL target. (A non crit with the same bonuses would deal 15-30 damage, with an average of 23.) So a 152 damage staff hit against the master of damage should be possible (albeit with another player providing GDW); is there anything else that could be added? If you only cared about the single highest damage rather than dps you could use Dodge This rather than Drunken Master. Judge's Insight won't work because it changes your damage type and I can't think of a way to get it back to elemental.