Ruivark, The Shadow Flame

When Ruivark, Shadow Flame enters the battlefield, you may cast a dragon spell with
converted mana cost X,
where X is the amount of mana spent to cast it.
Other Dragons you control have Double Strike
If a Dragon would leave the battlefield, shuffle it
into your library, then reveal the top card of their library.
If it’s a Dragon creature card, put it onto the battlefield tapped.