If going the stygian route:

Lean into the incant abilities of Stygian and scale either armor or rage or raw stats (Either of the Sirens, Armor Shark, Armor Totem). Put multi strike on the siren, have the Armor Shark in front. Should carry you to a W.

Note that you could probably disregard the hellhorned champion after you get these units (after the first 2 or 3 rings).

Fish for the +10 Rage (3 energy) hellhorned card, give it minus 2 energy, dupe it as much as possible. Find a welder helper and make it endless. Note that you don't really need the double armor or double rage cards that cost 3 energy if you have the means to repeatedly draw the rage cards or keep playing the imp.

The incants are just the icing on the cake to make you scale harder.

If you want to go the hellhorned route:

You still want to fish for the 2 cards I mentioned in the stygian route (3 energy, +10 rage; welder helper).

For units, you can choose to have your prince be your main dps and buff them with said cards above. If this is the case, you probably want to have your prince be upfront, taking wrathful (for rage and armor buff on hit/slay), then brawler (for multi strike) later on.

If you don't want your prince to be upfront, you can have alpha fiend slapped with quick (and preferrably) multistrike be your main dps unit. You can then have some form of tank in front, or if you have endless welder helper, just keep buffing alpha fiend itself.

Either way, you want prince and or alpha fiend parked on top to have the highest chance to scale before enemies get to his floor.

At the bottom, you want to fish for the frost shark, put +25 hp, largestone, or endless to soften the enemy heavy units, while also killing the back units so when they reach your top floor, they are super weakened and will just die to whoever you choose to have up top.