Of all the unfair strategies in Cube, the combo pieces of a "reanimator" deck have the most analogs to work with
Whether that's untapping, having infinite ETBs, or something more complex, they all break parity in one way or another, sometimes through manipulation of the stack
The only real downside is that your copy is tapped when created but as soon as you get to untapping it, you can start to cause some havoc
The color limit also cuts down significantly on the possible decks that can be built, making it less overwhelming than a game like Magic that lets you mix and match with fewer limitations
Mr Dragon himself is a low-cost card that builds up when youre bringing in dragon-type creatures
I would just caution against going crazy on these for arbitrage purposes simply because demand for this oversized card cant be huge