What did you use your masterball on in Pokémon S/V?

I used my first one on the second Miraidon. I used my second one on one of the returning Legendaries but I don't remember which one.

I don’t have S/V, so I’ll just say what I used it for in SWSH. I used it for Zacian.

I haven't used it yet. I only use the master ball as a last resort.