Daenerys, Mother of Dragons

When Daenerys, Mother of Dragons enters the battlefield, create three 3/3 red Dragon legendary creature tokens with flying named "Drogon", "Viserion", and "Rhaegal".
At the beginning of your upkeep, choose a dragon
you control. Until the beginning of your next
upkeep, Daenerys, Mother of Dragons becomes a
copy of it, except it's still a Human Queen.