Does Leyline of the Void affect cards that are discarded and would normally go to the graveyard?

Leyline of the Void has a replacement effect that reads: 'If a card would be put into an opponent's graveyard from anywhere, exile it instead.' This effect applies to any zone transition that would result in a card entering an opponent's graveyard — including discard.

Under CR 400.7 and CR 614.1, replacement effects modify events before they happen. When a player discards a card, that card would normally move from hand to graveyard (CR 701.7a). Leyline of the Void intercepts this transition and redirects the card to exile instead. The card never touches the graveyard.

This is significant because many discard-payoff cards care about cards being discarded to the graveyard specifically (e.g., Madness triggers still work because the discard event still occurs — CR 702.35 — but other effects that look for a card entering the graveyard via discard will not trigger).

Example: Your opponent controls Leyline of the Void. You are forced to discard Darkblast due to having too many cards at end of turn. Instead of going to your graveyard, Darkblast is exiled immediately. You cannot use its dredge ability on a future draw step because it is no longer in your graveyard.

Note: Leyline of the Void only affects opponents' graveyards, not your own. If you control it, your own discarded cards still go to your graveyard normally (CR 614.1, Leyline of the Void card text).