Arena of Glory

You must already control a Mountain as Arena of Glory enters the battlefield for it to enter untapped. If it enters the battlefield at the same time as a Mountain when you control no other Mountains, it will enter tapped.

If mana generated with Arena of Glory's last ability is spent on a noncreature spell that becomes a creature later in the turn, that creature won't have haste.

If mana generated with Arena of Glory's last ability is spent to pay any part of a creature spell's cost, including an alternative or additional cost, that creature spell (and the resulting creature) will gain haste until end of turn.