Reginn, the Rune Bound

Flying, Trample, Indestructible
When Reginn, the Rune Bound enters the battlefield or attacks, search your library for a
dragon card with converted mana cost {x} or less,
where {x} is the generic mana spent to cast Reginn.
Whenever a dragon you control attacks, dragons
you control get +3/+3 until end of turn.