Imperial Hellkite
Creature — Dragon
Flying
Morph 
(You may cast this card face down as a 2/2 creature for 
. Turn it face up any time for its morph cost.)
When this creature is turned face up, you may search your library for a Dragon card, reveal it, put it into your hand, then shuffle.
Matt Cavotta
Legions (LGN)
• #103Rulings
You do not have to find a Dragon card if you do not want to, even if you have one in your library.
(wotc • 2004-10-04)
The trigger occurs when you use the Morph ability to turn the card face up, or when an effect turns it face up. It will not trigger on being revealed or on leaving the battlefield.
(wotc • 2004-10-04)
Rulings
You do not have to find a Dragon card if you do not want to, even if you have one in your library.
(wotc • 2004-10-04)
The trigger occurs when you use the Morph ability to turn the card face up, or when an effect turns it face up. It will not trigger on being revealed or on leaving the battlefield.
(wotc • 2004-10-04)