I was able to take both of them down with Cryptic with no potions and above 70% health, use Nythera and Mritha.
Cryptic has a very strong defense setup, Use Stun on Abomination first, use Mritha's turn to increase defense, give Crawler the best damaging attack that Nythera has got (Void Spear, and other heavy fire attacks as well as keep absorbing health back whenever you get the chance).
Keep attacking crawler and take him down in the minimum number of turns cause he gets stronger every turn, after your 3 turn stun gets over use earthbound by Nythera on abomination and after that turn stun abomination again with mirtha and keep your defenses up with Illusion and Stealth. Use blind on abomination if you have cooldowns on your stun attacks and use every move at your disposal to keep crawler from executing those multi moves. And whenever you go below 50% hp , try to use illusion and use the Steal Potion move because it definitely worked for me, you might miss once but generally it hits (given the 50% chance). Abomination should not be that big of a problem if you keep stunning and blinding him.
I feel like cryptic is much better than deathknight or necro in this challenge because of the extreme defense capabilities and really good crit damage, my cryptic kept giving almost 800 damage on throw and around 1000 with rapid (my crit was 57). I used the same setup that is on my character page just Blade of Aww was shown instead of destiny weapons.
SWoT was also able to do it but had a much more tighter window of attack.
Sir leon is helpful but i prefer Nythera becuase she has healing moves (2 of them) and potions to go with em, mritha is very useful because of her stun and sheild, plus she damages around 300+ every three turns with her second skilll.
It took me quite a few tries, i played the challenge with Necro, Paladin, SWoT, Deathknight, Dragonlord (No artifacts), Soulweaver (i barely missed abomination with this armor as he nuked me right at the end) and even Paragon armor (even though it is same as necromancer), Ascended ChickenCow (got rekt by abomination again).
For non-da, i really think its next to impossible without having insane real life luck and the character missing all the attacks throw at them by those two. Other helpful guests would be Aegis and use good ice weapon because aegis weakens enemies to ice and any other npc with decent attack moves and the ability to stun and if possible also those who reduce the bonus by -50 or more.