So my level 61 Conjurer just got killed, may he rest in piece.
This is my 2nd try to finish the whole game with a hardcore character, I also have a still living level 71 Stormstrike-Shaman, but he kinda ran into a wall on the 3rd difficulty setting.
What is the easiest and SAFEST build to finish the game in hardcore difficulty?
I just want to get the achievements once and I think I know enough about all the locations and bosses to kinda know when I’m ready to take them on.
I just need something that doesnt just fall over when I’m not 100% focused for a moment.
I’m surprised your summoner build didn’t get you through the end of elite (I’m assuming it died in Elite, as I don’t normally get to ultimate till almost lvl 70).
Were you using the pokemon build from the build forum? I’m not following it exactly, just looked at it to see what he was doing differently to my first try to see what is weak and strong for summoners. With only a few pieces of good gear I find that it is cruising through. especially when you are hitting lvl 60s, as you’ve maxed out 2.5 summons, and hopefully have Og’Napesh book for a permanent 3rd summon. Then with devotions you get a 4th for 66% of the time.
Two other builds I’ve gotten through into ultimate (haven’t finished ult yet though, so can’t vouch for end end end game viability), are a sustain tank using sigils, retaliation, shield, concentrating on chaos/vitality damage. He doesn’t die easily 
Te other is a deathray guy, points in devastation for trash clear, and then beam everything to death for heroes/bosses, chuck out all the -resists you can, drop devastation on their head then stand and deliver with mirror on. they should be dead before mirror finishes. I’ve taken soldier mastery to beef up its defenses (health, DA), and some non permanent uptime OA buffs.
I’m sure you can do it
The worst mistake was to switch to a meele weapon I think.
I felt beefy enough and it worked out for 2 levels.
If only I had found a better ranged weapon before that I’d probably still be alive. But using a level 40 gun at level 60 felt stupid.
fair enough. although I play summoners to not have to attack 
1,2,3 repeat every now and then. move and loot!
A wind devil / storm totem build would work easily if you just want to spend your whole time running away. Not sure how you die with a pet build, doesnt really matter what weapon you have, you just never do dmg with those type of builds.
A 2h rifle Commando build works well IMO just cause you are always killing from far away, and can build tanky (My personal fav)
A sigil of consumption / doom bolt / devouring swarm build is pretty OP and drain tanks everything.
Main things is focus on defense for your devotion points, gears, and stat points. Damage is pretty easy to find just with skills and a few gear slots.
Also make sure you get the resist / hp buffs going on for your augments etc. Pretty much every build should get you to ultimate at this point.