I'd stay away from one off cards to tech the meta. As good as they are, you need multiples of the characters you run to benefit most from Dr. Doom's text. Devil You Know is great with this team up. Obviously, Centurious works exceptionally well with Doom here, but that is GA, so we skip it.

There is that new team up that when you discard it you can power up if you already have a copy in play. Run 4 of those. If you are just doing Doom/Underworld, that the extra team ups have a use after you get one in play.

However, this is where I would be tempted to run Chen and squeeze in a third Team....but ultimately it may not be as effective as using Black Rose to retrieve your power up.

What about, and I haven't built this yet, but I'm just thinking:
Dwarf
Black Rose
Doom/Technarx
Sub-Mariner/Nastir'h i guess
Doom
Maddy etc etc

Recruit Rose on 2; Discard dwarf to get Ritual Sacrifice (probably only 1 oe 2 of these as truth and justice should be primary)
Turn 3, recruit Doom (find whatever you still need); team up
Turn 4; pitch Technarx to something (ideally death's embrace to find submariner)
End of turn 4, KO doom to bring Technarx in
Turn 5, drop Doom

I think I may have to build this deck; it looks interesting

Edit: just realized the foolishness of no underworld 3 drop as that's the first turn death's embrace kicks in; back to the drawing board for me

I'm a really big fan of Umar. Her glass jaw to Blackheart hurts, but even then, she might be worth the risk. Filling your k.o. pile and your hand? Yes please!

Another option is to go backwards to the 3 drop IronMan from HoG and use him since he's a doom character. Might bot be the best choice, but with the added effect of foreknowledge, he's got to be a little good. Meat Market is likely the best choice though since he stays in theme.

Submariner seems like a good choice, since with MEatmarket you'll be able to cycle in to the other copies of him faster, bringing Meatmarket online faster. That also fuels BlackRose in her need to help power up her friends.

My build

Characters:

1-drops
The Dwarf-2

2-drops
Black Rose-4
Shathra-3

3-drops
Umar-4
Dr. Doom-2

4-drops
Blackheart-1
Submariner-4

5-drops
Dr. Doom-3
Thanos-1

6-drops
Madelyn Pryor-2

7-drops
Dormammu-2

8-drops
Dr. Doom/ or Noble Kale


I'll keep my pt and locations secrets. Til i really figure them out.

5 drop Doom and Technarx seem to have a great amount of synergy. His power ups will allow him to keep replacing the one that was stunned and in play already. Interesting...

so yay for more doom stuff in this set to work on this deck...!!