This is hard without a puzzle gauntlet running! Namor’s counter continues to increment if he is dead though, so if you have some sort of “send them away” capability you could probably do a decent job. So far i’ve tried to get a 2* ascended to 4* Magneto going, and Wiccan, but all the nodes available to me with health-ful enemies are too strong for them to last.
5mags onslaught. mag blue > namor green and red untill everything is dead.
nuke-wise, still less damage than a 3/4may+vision+5kang, vision yellow/blue > kang purple
I used 5* Vulture/Namor/Shang-Chi is the cheat code for this, but it isn’t very efficient. Drag someone airborne with 5* vulture and then use Shang-Chi to kill the other two, just make sure to leave the countdown alive. You can use Namor’s green or red if you have a surplus, but I did it on a team with boosted strange, who i threw airborne, and when he landed he would flames of faltine my unleveled Namor, and once he died it stopped incrementing the counter. But you could do this as long as you have the patience. Chase match-4 or linear match-5 if you want to maximize destruction with Shang, it doesn’t count regular matches.