Cheaty Mages

You look at a row of five monster cards fighting in an arena and secretively cast a double-strength spell card on a weak goblin.

The Wizardry: Bet on a monster tournament while secretly altering stats using spell cards. The arena judge dispels everything if spells exceed the magic limit.

The Hidden Choice: Drop direct attack spells early, or wait until the final reveal phase to drop subversion cards? It is fast, chaotic, and highly entertaining.