Cabal Therapy is its own game within a game, like combat or how cool you look shuffling when someone attractive walks up to your table
Metal means Steel, and is often the domain of any dual-type Pokemon with Steel as one of its types
The illusion ability has echoes of offspring, which probably isnt completely intentional, but still pretty great from a flavor perspective (as well as a deckbuilding perspective if you want to create plenty of ETB abilities or plan on going wide)
But the card draw ability gives decks lots of reach in the late game
Sideboard Usefulness: Dismember - It'll cost you 4 life to pay it, but can save you big in removing a Tarmogoyf before it gets too big to deal with
Royal Treatment gives a creature you control hexproof for the turn, while also creating a Royal Role enchantment token attached to it, giving it a permanent +1/+1 and ward 1 boost