2021-06-18 : Cards exiled by Laelia, the Blade Reforged are exiled face up.

2021-06-18 : If you play a card this way, it leaves exile and becomes a new object. If it returns to exile later in the turn, you can't play it again.

2021-06-18 : Laelia, the Blade Reforged has recieved an update to its Oracle text. The official text is listed above. Specifically, its last triggered ability doesn't care which player is exiling cards from the library or graveyard. Cards put into exile from your library or graveyard for any reason, such as the delve ability, cause the ability to trigger.

2021-06-18 : The last ability only triggers once for each time cards are put into exile from your library and/or graveyard, no matter how many cards were exiled at the same time.

2021-06-18 : You must follow the normal timing permissions and restrictions while playing the exiled card. If it's a land, you can't play it unless you have land plays available.

2021-06-18 : You'll still pay all costs for a spell cast this way, including additional costs. You may also pay alternative costs if any are available.

2022-09-09 : If a player is instructed to exile cards from their library "until" a certain event occurs, that player exiles those cards one at a time. Laelia's last ability will trigger that many times.