So there’s a few cards that have interesting triggers that care about when you exile cards. Laelia, the Blade Reforged is a good example, where she cares about when one or more cards are put into exile from your library or graveyard. There’s a few others, so we’ll go over how they interact with common exiling mechanics!

Laelia

For Laelia, there’s a functional errata to pay attention to first and foremost – it no longer cares who puts cards in exile from your graveyard or library. So if someone Nihil spellbombs your graveyard, Laelia will trigger once. Same goes for effects like Delve, but not ones that go to another zone first, like Flashback or Jumpstart being cast. Laelia and cards like her will almost always get just one +1/+1 counter for exiling cards from either zone from a single effect. However, there’s a few exceptions, like Cascade or Discover. Since these effects make you exile cards from the top of your library until some event occurs (finding a qualifying spell), then Laelia will trigger for each card exiled. (She has a gatherer ruling clarifying this).

Because you’re exiling cards individually and checking for qualifiers, they count as individual exiling events, unlike effects like Ashiok, Nightmare Weaver‘s +2 ability to exile the top three cards of target players’ library.

There are a few other cards that work similarly, like The War Doctor and Stonebinder’s Familiar, but they won’t trigger multiple times either except with things ‘exiling until‘ – so no luck with Demonic Consultation, or similar, but possibility storm lets you have all the fun.