Are triggered abilities optional to put on the stack? Or is it always triggered but then can be declined? Example if someone wants to react to a move trigger, before a showdown begins, could the player controlling the move trigger opt to not trigger it at all? Or can they only decline the effect on resolution?

Ruling: It depends on the trigger's wording.

"You may" triggers — If the ability starts with "you may" (e.g., "When I move, you may pay [1] to draw 1"), the controller chooses whether to place it on the chain at all when the condition is met (Rule 383.3.a). If they choose not to, it never becomes a Pending Item, and no reaction window opens.

Mandatory triggers (no "you may") — These must go on the chain when the condition is met. Opponents will get a reaction window.

Triggers with a cost but no "you may" (e.g., "When I move, exhaust: deal 1") — The ability goes on the chain (mandatory trigger), but at the Pay Costs step the controller may decline to pay, removing it from the chain without it ever resolving (Rule 404.2).

Your move trigger example

If the move trigger says "you may" (like many move triggers do), the controlling player can completely opt out — no chain, no reaction window from the opponent, the showdown proceeds immediately after Cleanup. If it's a mandatory move trigger (no "you may"), it goes on the chain and the opponent gets to react before the showdown begins.

Important note: This was a rules update as of March 2026. The old FAQ entries saying "all triggers always go on the chain" are outdated — the current rules (383.3.a) now let "you may" triggers be skipped entirely at the player's discretion.