Short answer: Runic Wristbands
Long Answer:
The whole build is designed to build power, mastery, and damage with various mechanics.
My starting stats are pretty great, but nothing in comparison to the growth after just a few turns (screenshots in the previous post)
You can continue to grow your mastery with a runic belt.
The spell combo of Climb the Peak, and Dark Ice makes this grow very fast with 5+ matches each turn.
Power growth from Royal Sword + Royal III, heroic effort, Climb the Peak, Deep Magic. There are synergies on synergies in this build.
Climb the Peak adds big gems to the board, big gems give 7% power bonus for each on the board. Power increases spells too, so you get results like this:
adding 3 big gems gores from this:
to this:
Both Climb the Peak and Deep Magic grow to very large numbers as you continue the fight through many turns.
Fortify the Dead is only there to remove skulls so I can keep the dragon alive longer and build up for the final skull damage turn. The necromancer Ultimate is perfect for this. You just fill the board with ultimate gems as much as possible and then trigger them to fill the final board.