Does Leyline of the Void stop a card from going to the graveyard before a graveyard trigger can see it?

Leyline of the Void has a replacement effect (CR 614.1) that modifies where an opponent's card goes: instead of being put into their graveyard, it is exiled. Because this replacement effect applies before the card reaches the graveyard, the card never actually enters that zone.

Triggered abilities that watch for cards entering the graveyard (e.g., 'whenever a creature is put into a graveyard') use the event of a card entering that zone as their trigger condition (CR 603.2). If the card is redirected to exile by Leyline of the Void, the 'enters the graveyard' event never occurs, so those triggers never see it and never trigger (CR 614.6).

This is different from a card that enters the graveyard and is then immediately exiled — replacement effects change the event itself, not the result after the fact. The card goes straight to exile; the graveyard is never involved.

Example: Your opponent's Gravecrawler is destroyed while Leyline of the Void is on the battlefield. Gravecrawler goes to exile instead of the graveyard. Your opponent's Zulaport Cutthroat, which triggers 'whenever a creature you control dies,' does NOT trigger, because dying means going to the graveyard (CR 700.4), and Gravecrawler never went there.

Note: If an ability exiles a card from the graveyard as a cost or triggered effect, that is a separate action and Leyline of the Void is not relevant to it — Leyline only intercepts cards on their way to the graveyard (CR 614.1c).