As a thematic update would it be possible to make Lore of the Great Plagues a multi-selector:
Lore of the Great Plagues:
Avoidance: You gain a +1/2/3 saving throw bonus against poison and disease.
Acceptance: When targeted by any opponent's poison or disease effect - gain 1 imbue dice and 5/10/15% movement increase for 20s.
Rank 3 for both: Gain 5 Poison and Negative Spell Power.
Just something along the lines of "you fool... you dare to disease or poison a Blightcaster!"
Also I don't think I've ever specifically selected gear, feat, or enhancement to gain saves vs. poison, disease.