Viserion and Rhaegal, Chained

Viserion and Rhaegal, Chained enters the battlefield tapped.
Flying, devour 1
When Viserion and Rhaegal, Chained attacks, it
doesn't untap during its controller's next untap
step.
Far beneath the Great Pyramid, two of Daenarys' children lie chained in the dark, their cries unheard
but felt far above.