I imagine the variant isn’t QUITE out yet, but there’s no way this isn’t this week’s unlock, so let’s have a thread for it, ready for when it DOES become available.
It’s out now.
Good luck!
Tried putting over 10 devices under Savage Mana in Omnitron IV while using each of Haka's "Haka" cards... no unlock.
On my tablet, so no log for this one, but Haka in Temple of Zhu Long. Used Enduring Intercession, took a bunch of environment redirects, died, and was resurrected before winning. No unlock.
Currently working on tanking a mess of fire damage in Magmaria using Enduring Intercession. Unfortunately the first Behemoth came out on turn 1...
Took damage from Megalopolis stuff (2x Monorail, 1x Targeting Innocents, 1x Impending Casualty) down to 1 HP with Haka, recovered all the way to full, won at full HP with Intercession still out. Nothing doing.
It’s not have Haka take all the damage from the wasteland cryptically have 3 dominions in play, and savage mana gloom weaver for 74 damage (and essentially redrawing giants whole deck in the process)
I just had a hell of a failure.
Vs. Ambuscade in Magmaria. Used all 4 damaging powers, had Enduring Intercession out. (And took 15 damage through it in one turn.) Had every single device, all Magmarians, and one Dodongo under Savage Mana, then used a Haka of Battle (which emptied my deck) and dumped every card I had (32). Dealt Ambuscade 67 damage in one Savage Mana burst, bringing him to -51.
NO UNLOCK!
So, I’m guessing one of three things is true.
First, I either had to have ALL non-hero targets, but since I had all villain targets and one of each environment target, that seems a bit unlikely.
Second, I did something I wasn’t supposed to. Maybe I shouldn’t have used Mere or Taiaha, for instance.
Or, third, Magmaria is not the correct environment.
I have two ideas if anyone wants to try with me in different environments
1) heal more health than your maximum (more than 34)
2) deal 0 damage
Possible environment to try: Freedom Tower, since the name of the power is Die Hard
What's the most METAL environment we haven't already seen?
Insula Primalis? Pretty METAL
Court of Blood? DEATH METAL
Dok'Thorath? Beat the system, man.
Enclave of the Endlings? Uhhh...
The only other METAL environment I can think of is The Block.
Clearly Silver Gulch. 
I tried Freedom Tower. Kept Haka and Ambuscade at full health, Savage Mana’d all of his toys, had 3 Dominions and Intercession out (also Punish the Weak, Ta Moko and Mere) and hit him for 66, killing him from full.
No dice.
failed attempt:
Ambuscade VS Haka, and the rest of the XPW team in Rook City.
specifically i was trying to go for a big amount of damage with Savage Mana. everyone was alive, and ended up doing 34 pts of damage. nothing really special happened, so i dunno what else to put besides that.
Took Haka down to Rook City, tried out a game in which he never dealt damage (against Ambuscade). I also used all the Hakas, and used one Haka with a 9-card feed, as well as redirecting a ton of environment damage to Haka.
No unlock.
Failed attempt: Give Haka the title of "Reckless" (which has him gain an HP the first time each turn he takes damage). However, I lost that game, so it's still within the realm of possibilities (though I hope not, since that would be a pain).
His incap on the X-Treme card is him in a volcano with Ambuscade looking down at him. That suggests Ambuscade and Insula Primalis or perhaps Magmaria?
Well, it wasn't beating Ambuscade in the Final Wasteland with Haka the only hero down and everyone else at full HP.
It'd be hilarious to me if using Ambuscade ends up being a requirement, considering he's usually the go-to choice for finding unlocks for everybody else.