Well take a look at these.
I managed to get 11 or 12 to reliably agro.
On my shield which is the one in the pics I could survive forever. If it would let me I could herd the whole island and likely wouldnt fall.
On my Elec brute its a bit more tricky because the DE do a fair amount of toxic and while I patched the hole pretty good its still a hole they can get through every now and again, but if you stay on your toes and leverage melee core, rebirth radial and energize wisely its infinite survival also.
The cool one is the radiation armor brute, it has mechanics that allow ot to survive intimately also, the health bar moves alot bit you are never in any danger.
Haven't tried it with fire or invul yet.