Arena of Glory enters tapped unless you control a Mountain. : Add . , , Exert Arena of Glory: Add . 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.)
If an exerted permanent is already untapped during your next untap step (most likely because an effect untapped it), exert's effect preventing it from untapping expires without having done anything.
07-06-2024
wotc
If the mana generated with Arena of Glory's last ability is spent on two different creature spells, each of those spells (and resulting creatures) will gain haste until end of turn.
07-06-2024
wotc
If mana generated with Arena of Glory's last ability is spent to cast a noncreature spell that creates tokens, those tokens won't gain haste.
07-06-2024
wotc
The mana generated with Arena of Glory's last ability can be spent on anything, not just creature spells.
07-06-2024
wotc
If you gain control of another player's permanent until end of turn and exert it, and then that player regains control of it, it will untap during that player's untap step.
07-06-2024
wotc
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.
07-06-2024
wotc
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.
07-06-2024
wotc
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.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.