Any good bleed champ is nice but I found vision worked well if you're patient his S1 and S2 damage bypasses safeguard and power drains to avoid any specials
Yellowjackets biosting also bypasses it from what I've heard. The above posters are correct that any damage over time ability also will whittle them down. Bleeds, frostbite, etc, especially on Wolverine or X-23 are all good.
Otherwise, Elektra, Gwenpool, or Kingpin all can reduce defensive ability accuracy.
AA would be amazing between the bleeds and poisons alone, but then once you get neurotoxins going as well that'll reduce defensive ability accuracy while causing lots of damage
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Otherwise, Elektra, Gwenpool, or Kingpin all can reduce defensive ability accuracy.
Iceman too