Relic Run my followers had +1 health but everything was so much stronger and only 4 core health was so hard! I must've went through 20 runs before landing on this very unassuming successful run.
1 - Supplicant - +2 Faith and +2 health upon death (strategically the only death effect in party)
2 - Revive everything to 1 health once all dead (doubles all death effects!)
3 - Start of battle, copy random death effect (always +2 Faith and +2 Health)
4 - Start of battle, copy random death effect (always +2 Faith and +2 Health)
5 - Dragoon - Attacks an additional time x 3 and when attacks, deal 3 random damage (4+3+4+3+4+3+4+3=28 per turn!)
6 - Medic - Adjacent allies get +1 health with each attack and +1/+1 to adjacent allies
7 - Dualist - Switches Attack and Health with each attack and (CRUCIALLY) this follower gains DOUBLE STATS.
8 - Familiar - Gains stats equal to adjacent followers and (ALSO CRUCIALLY) this follower gains DOUBLE STATS.
Potions
3 x Attack Potions on Dualist (for +2 each potion with additional trait) for +6 base attack.
Traits and Strategy
Strategy 1 - Buff the Attackers
Pump health as much as possible to Dualist. With this build, by the time Dualist attacks it has already gained +12 health and +2 Attack (+6 health and +1 Attack x 2).
Strategy 2 - Exponential Attack Growth
After Dualist is buffed with +12 health and +2 on turn one, with base stats of 7/4, it becomes 9/16 before it's first attack. Stats switch upon first attack to DOUBLE and become 32/18. Next attack, 36/64, then 128/72, etc.
Everything in front of Dualist gained +6 health and all the way up to the Dragon quarry, it typically took three rounds to reach the Dualist and I never lost any core health. This means by the time Dualist is taking hits, it is already very comfortably at 128/72.
Let's not forget about the Familiar.
As Dualist has been gained double stats each switch, familiar is also gaining it x 2, going from base 2/4 to 6/28 before its first attack. With each stat switch from Dualist, over the next three rounds, it progresses 52/72 -> 116/136 -> 244/208.
By turn three I was consistently down to only the Dualist and Familiar reaching the hundreds. Typically the Dualist would die as the lower stat would get crunched to 0, but Familiar always survived (!!!).
It was only at Endless Mode that I ever engaged the non-support revival of all followers, and while only 1 health, attack stat was safely intact. This meant so long as Dualist landed ONE HIT, Familiar received quite literally hundreds of health and retained its attack power.
When I started this run, I thought this hodge-podge group was not going to make it, as I had other runs with very amazing synergies (my favourite is always getting Ranger with random attack damage, coupled with turrets to spray and pray). I actually HATED Dualist quite literally right up until this run, when I realise it was the lynchpin in my most favourite run yet!

