Arena of Glory enters the battlefield tapped unless you control a mountain.
T: Add R.
R, T, Exert Arena of Glory: Add RR. If that mana is spent on a creature spell, it gains haste until end of turn. (An exerted permanent won't untap during your next untap step.
![Arena of Glory (Borderless) [Modern Horizons 3]](http://www.cosmicgames.com/cdn/shop/files/3d7d07bb-b875-4a6d-8b87-4187e823af75.png?v=1773366987&width=1445)
