Sunder to bring it to 95
Latent sunder to bring it to 85
Amp to bring it to -15 (did not know it's 100% effective if sundered monster)
Jewel to bring it to -25
I honestly cannot find anything in the web updated pirperly for a summon necro. Build lacks love and to be frank, it is so much fun.
I think maxroll mentioned on how the Amp.dmg work 100% after sunder bone break and it looks like it. Immune Monsters melt no problem.
But the protector stone, only minus res would be required, but how to say if it works for sure.