The Dagonborn, Dragon Slayer

When The Dagonborn, Dragon Slayer enter the battlefield search in your library
for an Instant - Thu'um card and put it in
your hand, shuffle your library.
When a dragon creature is destroy,
tap The Dagonborn, Dragon Slayer and put an
Instant - Thu'um card from your exile to
your hand.
When you use an Instant Thu'um spell,
put a +1/+1 counter on The Dagonborn, Dragon Slayer