Verz Ouroboros

Once per turn: You can detach 1 Xyz Material from this card; activate 1 of these effects. Each of these effects can only be used once while this card is face-up on the field. ● Target 1 card your opponent controls; return it to the hand. ● Send 1 random card from your opponent's hand to the Graveyard. ● Banish 1 card in your opponent's Graveyard.

Can this xyz card's effect be activated during either players turn at any time, or only during the controller's turn

Only during the controller's Main Phase; it's an Ignition Effect.

Thank you.