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://paradoxtcg.com/cdn/shop/files/7b10e0e0-ea5b-51d9-8fbf-c9c952e1bd74.png?v=1723046345&width=1445)
