Isareth the Awakener

Because all attacking creatures are chosen at once, a creature returned this way can't attack during the same combat as it returns, even if it has haste.

Because to die means to be put into a graveyard from the battlefield, a creature that is exiled instead doesn't "die." Abilities that would trigger when it dies won't trigger.

Isareth's triggered ability goes on the stack without a target. While that ability is resolving, you may pay {X}. When you do, a second ability triggers and you pick a target creature card to return. This is different from abilities that say "If you do . . ." in that players may cast spells and activate abilities after mana is paid and the target creature card is chosen, but before that card is returned.