[/quote]I used to run a similar build. I posted about it on Reddit a year ago, but I think the advice is still relevant.
[quote=just quoting myself]
I have exactly the build - I sometimes can play during work, but need to immediately stop if work comes up - this build won't die even against base game world bosses (and some add heavy dlc world bosses). It is my go to build for grinding in skyreach, as I just gather up half the mobs on the top floor and go and make a cup of tea - easy companion levelling. Works great in pug dungeons as you won't die to anything but mechanics even if your team sucks.
Obviously all heavy armor, all enchantments for max health, mundus for max health. I use training gear for bonus XP for companions, but small pieces in divine will slightly boost health more.
Warden class, because your sets will proc your major toughness, buffing your incredible health pool by another 10% (60k+) and your healing and damage scale off max health. The bear is free extra damage, and several damaging skills also scale off max health, for when you play more actively. I chose orc for the extra speed, health, and the ability to self-heal fits the theme.
Crimson twilight and leeching plate both proc off damage taken and do AoE damage scaled off of max health, and heals you based on damage done. I have sword of one set, shield of the other, so my back bar has an ability altering weapon for when I'm playing more actively.
Monster set is scourge harvester - it does single target damage and heals scaling off max health, but also increases the healing received from all 3 sets.
Note - if you "rubber band" to keep your game on, so this build kills things as they respawn, it will break terms of service and you risk a ban. As long as you are checking on the game often enough to avoid autokick it is just creatively using in-game mechanics.
Tldr - there are sets that proc from taking damage, do damage and heal, all scaling off max health. Generally you become more unkillable the more enemies you fight.
Edit - grammar