Activate Jan Jansen's first ability by tapping it and sacrificing an artifact creature, creating three Treasure tokens due to Xorn.
Activate three Treasures by tapping and sacrificing them, adding 4 due to Goldspan Dragon.
Activate Crab Umbra by paying 2, untapping Jan Jansen.
Activate Jan Jansen's first ability by tapping it and sacrificing an artifact creature, creating three Treasure tokens due to Xorn.
Activate Crab Umbra by paying 2, untapping Jan Jansen.
Activate Jan Jansen's second ability by tapping it and sacrificing a Treasure, creating two 1/1 Construct artifact creature tokens.
Activate two Treasures by tapping and sacrificing them, adding 2 due to Goldspan Dragon.
Activate Crab Umbra by paying 2, untapping Jan Jansen.
Repeat.
This intricate engine relies on Jan Jansen, Chaos Crafter acting as the ultimate catalyst, turning sacrifices into an absolute windfall of tokens. Goldspan Dragon quietly pulls double duty here: not only does its static ability supercharge every Treasure you crack to yield double the mana, but its presence also feeds into the combo's explosive math. Meanwhile, Xorn acts as a brilliant multiplier, ensuring that every time Jan Jansen spits out Treasures, you get a bonus piece of loot to keep the cycle going. To tie it all together, Crab Umbra enchants Jan Jansen to continuously untap the artisan for a modest mana fee, allowing you to fluidly alternate between sacrificing creatures and noncreature artifacts until you’ve buried the board in infinite resources.