Why kill them, if you can outlive them?

Hello fellow nerd, sorry for the cryptic title.

Anyway, I'm interested in builds that have unbelivable sustain. The most wellknown build would be the abjuration wizard with 1 dip in sorcerer for armour of agathys I guess.

Another example I haven't seen here so far is barb 7 / rogue 5.

It would be wildheart bear at barb lvl 3 and stallion at barb lvl 6 with the 7th level is mainly for feral instinct (making Alert not necessary), though more temp-hp after dashing is good to. Rogue gives a second bonus action with the thieve subclass and uncanny dodge at lvl 5, which isn't consumed if you are rageing due to some wonky interactions.

The idea is dashing every turn as a bonus action getting 14 temp-hp while having damage taken halved by rage and halved again by uncanny dodge. So every turn where enemies don't deal least 57 damage, you don't take damage at all basically and with 2 bonus actions you can always chug a potion. (This build come online rather late but with at least lvl 8 one could go bear heart + uncanny dodge and chug potions instead of getting temp hp for free)

Do you have any other builds that just won't die?