Rosette, Friend of Scales

+2: Reveal the top card of your library. If it's a dragon, you may cast it as if it cost mana of any color until end of turn. Put it into your hand.
-3: Search your library for a dragon, reveal it, then put it onto the battlefield tapped. Shuffle your library.
-10: All dragons you control gain +X/+X and unblockable until end of turn, where X equals the number of dragons you control.