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 [Modern Horizons 3 Prerelease Promos]](http://paradoxtcg.com/cdn/shop/files/554255.jpg?v=1720555749&width=1445)
