I once managed a total of around 37-ish damage from having Haka eat a whole load of citizens, then use Haka of Battle to ditch his whole hand (about seventeen cards) in order to finish off Dawn. Who had either three or four hp left. Because I could :D.
Our current record of damage dealt to a villain was dealt by the villain herself - Akash'Bhuta with By Any Means on her and a whole load of limbs out versus End of Days, with the bounty, naturally, destroyed after she whacked herself for a zillion damage. End total was about 109 damage dealt or something like that. wasn't enough to kill her - she had about 42hp left. But very satisfying - main reason for doing the End of Days, really, was "Eek, she's getting rather a lot of stuff out, and so's the environment - we should probably try and take 'em down quickly…" :D.
I once managed an arbitrarily high number (read: not infinity, but close enough to count) using Absolute Zero, Fixed Point, the Isothermic Transducer, and Twist the Ether. And then doubled it with Coolant Blast. Basically, I play Frostbound Drain. Deal the villain 4 cold, deal myself 4 fire. Because I took fire damage, I deal one target 4 cold damage; I select myself, change the damage type to fire and increase it by 1 for Twist the Ether, and lather rinse repeat, increasing the damage until it's basically infinite. Because Fixed Point, I don't die. Then Coolant Blast totals up all that damage that I just did and deals it again in a single blow.
The Tachyon and AZ examples aren't one hit, and neither is Akash. Someone hitting themselves because you hit them (like Akash's limb self-harm) doesn't count as a single hit either.
AZ was too one hit. It took several hits to build up to it, but once I was done preparing the Coolant Blast would have done 1 Target X Cold damage, where X is the amount of fire damage I'd taken. That total being an arbitrarily high number; because I was indestructible, I could have easily made it total 1,000,000 if I felt like it.
The infinite chain reaction of hitting myself for fire causing myself to hit myself for MORE fire would eventually cause me to hit myself for (one hit) of 1,000,000s of damage, which would cause me to deal one other target 1,000,000s of cold damage in a single hit. The question was what was the biggest single hit you've ever done; there was no rule saying I couldn't hit myself millions of times for consecutively stronger hits first to make the last one more powerful.
H=3 game against the Chairman, bringing Bunker and Unity, and you walked away with a win? I must say I am impressed! That is not an easy accomplishment at all.
Even with a villain deck of all targets you would get a max of 25 cards from it, and that's only 50 damage. You'd need to use Realm of Discord's imbued Vitality and eat every ongoing the heroes put out too, and I don't think you could add 50 additional cards before the other heroes beat you to death!
Did you add the +3 to each instance of 2 damage? That's not how it's calculated, it's add to the total at the end. So 10 cards under Savage Mana would be (10*2+3) 23 damage and not (10*(2+3)) 50 damage.
EDIT: Bah! Forgot Haka of Battle so it might have been possible.
Still, Haka of Battle only increases the first instance of damage, so if you dumped 20 cards your damage wouldn'd be 22 22 22 22 22 22, it would be 22 2 2 2 2 2 2. Still not enough for 160; especially without Obsidian fields to boost you.
I posted a short time ago with a very similar situlation. We were playing the new Gloom and Haka had Savage Mana-ed every target in his deck as well as a couple enviroment targets. He also had every card in his own deck played out or in his hand. When he finally let loose it was 18 cards under mana for 36 damage plus 33 cards in discarded to Haka of Battle for a total of 69 damage in one shot.
Solely on his own Chrono-Ranger can manage 92 damage in one turn. With the perfect team, environment, and set up I think he can manage 172 in a single turn against a single target.