Xyz Override

The effect "If an Xyz Monster on the field activates an effect by detaching its Xyz Material(s), you can banish 1 card from your hand face-down instead of detaching 1 Xyz Material. Each player can only use this effect once per turn" is an effect that does not start a Chain. (It can also be applied during the Damage Step.)

The effect of "Xyz Override" can be applied during either player's turn. The effect can be applied once by you and once by your opponent per turn.

This effect is applied when an Xyz Monster in the Monster Zone detaches Xyz Material(s) as a cost to activate an effect, and the player activating that monster's effect banishes 1 card from their own hand face-down. (You cannot banish a card from your hand instead when Xyz Material is detached as part of an effect resolution.)

Even if an effect is activated by detaching 2 or more Xyz Materials, such as "Evolzar Laggia," you can apply the effect of "Xyz Override," but you can only banish 1 card from your hand as a substitute for the Xyz Material. (You cannot banish multiple cards from your hand to substitute for multiple Xyz Materials.)