tomb of heretic cant be done, or only with the right potions and a lot of patience and player skill.
I cant.
But what I (or this build) can do is farming totems, and the other 4 dungeons until you get a full set and reroll a new build with the set you found or grind until you get enough gear upgrades and do heavier content later with the mortar trap shieldbreaker.
I grind totems and dungeons. Save every legendary and blue item in gd stash until I have enough and upgrade my hero.
Basicly if you find the helm recipe for a good set, you can grind enough mats to craft the helm 4x and reroll / transmute the helm long enough until you get the full set.
I already found the pyran offhand, and shoulders, and helm recipe.
Now I will grind enough eldritch essence to craft the helm 2x and get the full pyran set :))