Considering only L3 and L4 spawn, here are the average resists
Abyss
56/53/23/35/38
Arachnid
54/38/40/71/34
Cold Blood
47/45/38/47/36
Undead
44/28/56/46/38
Vermin
39/25/8/15/15
Now, my thinking here is to make Radiant Scimitars for doing the main spawn, and Slayer Bladed Staffs for the Champs. If you really look at the numbers you can get away with two Scimitars for doing all 5 spawns. I only need 35% DI to hit 100% and I don't need any SSI.
Max Hit Mana Leech (Reduced to using NO void orbs)
44% Hit Stamina Leech
44% Hit *1*
44% Hit *1* Area
35% Damage Increase
*1* = Hit Lightning and Hit Cold Area for Abyss, Vermin and Cold Blood spawns
*1* = Hit Fireball and Hit Fire Area for Arachnid and Undead spawns
Cheap build only costing 4 Relic Fragments and no special ingredients. So 8 relic frags for two Radiant Scimitars capable of tearing up all 5 spawn types.