Koryuu, the Frozen Emperor

Flying, Intimidate, Shroud
Whenever Koryuu enters the battlefield or
attacks, Create a white Aura enchantment token
named Frozen attached to another target creature
or artifact. The token has "Enchant permanent. Enchanted permanent doesn't untap during its controllers untap step. {x}: sacrifice frozen. X is
the cmc of the enchanted permanent. Activate
this ability only as a sorcery"