Pick Marris, don't get hit. That's pretty much it.

Play on lvl 0, be fully geared, infinite pull range is nice but I like the safety of two dashes so take any other sign. The Sign of The Helper seems bugged on the final boss and tends to miss the hit box. Since we are going Mort best in slot is looking to be The Sign of The Summoner.

Roll for Justice, Time, and what ever, probably Mort.

Justice -
Divine Shield - For a get out of jail free card.
Celestial Wings - To stay moving around quickly while attacking.
Reprisal - Just because everything else left is trash. Maybe a random stun will save your run.

Time -
Gem High - Skill is broken, DPS goes through the roof during enemy rush phases.
Warped Strike - Deal more dmg, get more exp shards to buff Gem High.
Force - To make up for not taking infinite pull range.
Every other skill is also pretty nice, can take Time Field for extra safety or The Summoner for more DPS.

Mort -
Mayhem - Free dmg
Ravens and Phantoms - Enable Mayhem
Execution - More exp to buff Gem High
Skeletons - During the 19 minute enemy rush you can build up so many skeletons that you can let them overrun the last boss.

I feel like the only hard part of the run is the early level green slime rush, if you can dash around that phase with out getting hit you should then be able to scale into a killing machine. Use Celestial Wings and Gem High to stay moving and collect all the power ups scattered across the map. I like to switch between auto attack and manual aiming. During gem high and Celestial Wings fly around the map using auto attack to blow up everything while looking for shrines. During boss and elite enemies switch back to manual aiming to burn them down.

GG EZ