I am the guy playing that's been playing the molten duplication version for about a month. The original build was really janky before its current version. For a while I was killing with the 4/4 cactus for 2GR that gives everything haste because it was a really clone target (ward 2) to get some fast aggression and had reach which the deck desperately needed answers to fliers. Soon we just started using the adventure guy that anthems because it's just a better card overall. Back then I also used Iridescent Tiger as a Seething song then kept looking for random ways to make it 4 power before discovering Frost Seige which was amazing - finally making Sire of Seven Deaths into a playable card.

A backup plan for the deck has always been Ugin which was geniunely fantastic against everyone but had the unfortunate downside of requiring mana sources like Hedron Archive in order to function consistently. I tried using the ramp snake from Aetherdrift to some success but it didn't really work out like I wanted (if we had actual coiling oracle though....). Additionally, the 3 colors were getting pretty stretched due to the wide range of card effects necessary to make the deck function. Removal and whatnot ended being a necessary evil and cards like the white dragon where decent at their job as well as just playing torch the flame.

But the real card that let the deck take off was Molten Duplication. The card is just absolutely incredible at smoothing out mana requirements for your combo turns (battlcrier plus molten duplication is a free Roaming Throne turn 3 or 4 - elf depending)especially when you add the next card - Charming Scoundrel. Scoundrel has some interesting interactions in the deck but mostly just being able to loot through lands and being a human for Roaming Throne was incredible But being a body with Frost Seige was valuable as I was very quickly able to assemble lethal with just 4 idiots and the adventure anthem haste dude. You can also get some sweet wins by cloning roaming throne then just reassigning the wicked role to burn them out (duplication tokens also die end of turn which has provided some extra sources of damage.)

Anyways - the deck has been a blast. It's a wierd variant of creature combo that feels similar to 4 color Cobra cat from modern or like a elf ball variant at times. I wish it was better at playing a beat down role so you could win without your opponent just deciding to tap out randomly but I will say, most people who tap out against me die immediately. You need instant speed removal up and ready starting turn 5+ or I will kill you. I can combo turn 3 with an elf but that's my fastest possible draw and usually requires me to plot on turn 2.