I think La Junta cards coz they are not really bonus dependent card, though +2 damage really helps alot but in winning the round their really rely on their abilities, they have some SOA Bryan and Tank, attack manipulation Gatline and Emeth and power manipulation, Trish and Dean

Jungo cards are good against Nightmare too, Skeelz too but Caelus is ban this week

I have decent luck with Skeelz vs. Nightmare.

Sasha, Sandro, and Chiara are all very solid vs most Nightmare characters.

Ghumbo is still a beast though.

Stop ability cards do wonders against all three.
Pan becomes a 7/3
Oshitsune becomes a 4/7 (worse than Zdrone)
Ghumbo is still a 7/7 but much easier to beat without his attack manipulation.

Skeelz is a good bet as well, sinse they don't care about SoB. and their abilities are much stronger than Nightmares. plus they generally outpower Nightmare.

Mono Jungo, Askai trumps Ghumbo with greater - attack, Boohma eats Oshitsune. All of Jungo's staples have 7 power or greater, so you match up with their high powers (Pan, Sheitane) very well. Just let Azgroth through, his 4 damage isn't much for a 4 star

Skeelz. And take cards like Danae and Chiara to counter Ghumbo.

Bryan (matches evenly w/Ghumbo, handles Oshitsune)
Trish (handles Oshitsune)
Dean
Wardog
Rolph (handles Ghumbo, Pan)
Toro (handles Ghumbo, Pan)
Leviatonn (handles Oshitsune)
Platinum (handles Oshitsune)

Junkz works fine, too. Rowdy beats Oshitsune. Gibson's SOB is a serious headache for Nightmare. With Gil and Tremorh you can overpill.

I tried GHEIST yesterday and it was going fine, when i came this morning, a horde of Roots kept popping up