Marvel's Midnight Suns

I don't know who needs to hear this, but if you can get cards with Conceal, you can cheese entire rounds. Just did it with Strange, and I know Hunter has an ability for it.

You should be able to use the combat item Vial of Shadows on any hypothetical Round 3 as well, and since combat items don't get used in THREAT rooms, you can cheese every third round with every hero.

UPDATE: Hahahaha so apparently Ghost Rider's Straight to Hell also works. Basically, if you can de-aggro the attack phase, you can skip through these rounds with ease. Feel free to update this with a thread of hero cheese(s).

The threat room is pretty hard at first, but there is a three item combo that makes it much easier. I did all heroes in a row so I could track which ones I had completed (can only do threat room once per day, after that they grey out) by saving after each success. I did this at level 20, and Magik seems to count twice as much as the others for some reason - I had to do all base heroes, even with Deadpool installed and recruited. Not sure how it would be if you have the rest unlocked.

Equip the items "fury totem" "evil eye totem" and "ironoak charm"

These items scale off enemies targeting the hero, and there is only one hero per threat room so it works really well.

Ironoak Charm gives a huge block based off the number targeting you. Use it at the start for most characters to get the most block, but those that generate block themselves (Captains) or heal (Wolverine, Hulk, Nico) could hold it as a backup instead. I always opened with it except for on Captain America, since he gets block for days.

Fury Totem gives you two turns of drawing cards upon KO, making it much easier to chain kills the first two rounds

Evil Eye totem applies 2 stacks of Mark to all enemies targeting you, giving you card draws back upon KO

Open every fight by using all your items, and try to keep the barrels for the later waves. You just need to kill one target per card use to keep it going. If you won't get a kill with a card, make sure it sets up for a kill. Was pretty straightforward with this setup, just spam cards until the waves are clear, then absorb the last wave with your Ironoak charm

Also, definitely make note of the conceal or hellmouth options others pointed out. I didn't need it, but it would cut down on the number of rounds you need to play

This may appear as daunting at first. Especially with characters like Scarlet Witch/Nico due to them not being as strong.

But you actually require very little effort in order to build better decks. You can also modify the cards for them to offer bonuses or extra damage.

You can also use the same attack over and over as it’s guaranteed to re-roll on the card deck if you only use that one + if each use equals a KO (ie: Hex bolt for Scarlet Witch, it starts with 2 chains but scales up to 5 chains, guarantees a KO at max chain streak).

You can also use Agatha’s Cauldron to create “Vial of Shadows”, which gives concealed for a turn, you can then end the turn and nothing will attack you. You are to use this on the third turn to skip to the end. Consumables do not get used up, so you can skip the third turn for every character using this method.

Doctor Strange, Blade and Hunter also have cards with “Concealed” stats on them, so these three will be super trivial compared to the rest. As for the rest, make use of high damage, knockbacks, forceful knockback etc. You’ll get it in no time if you simply upgrade all your cards and modify them.