Does Azir Ascendant's "Use only once per turn" restriction apply to each individual Azir or to the ability globally across all Azirs?

Ruling: Each individual Azir, Ascendant can use their own ability once per turn. The restriction is per copy of the card, not a global limit on the ability.

Nuances:

• If you attach a Svellsongur to give Azir the ability again, each instance of the ability can be activated separately once per turn