niv-mimic

You've got a few extraneous things going on here that could be trimmed for some better performance. Copy Artifact and Copy Enchantment don't really have any place in this build, as you aren't running many of either type, and neither type fits into your dragon theme. Curiosity isn't necessary and doesn't have great targets, as it's essentially a +0 until you attack with it twice beyond the Niv-shenanigans. Basilisk Collar isn't really worth the spot, as you don't need big dragons to have deathtouch, and lifelink is nice with big dragons, but you'll almost certainly win the game with damage making the life gain aspect moot. Instead, I'd up the land count to 21 and check out the following:

Mind Stone- helps you accelerate into your dragons and isn't a dead draw when you don't need the mana
Orb of Dragonkind- same as above
Thorn of Amethyst- basically won't affect you at all and will cripple a good portion of opposing decks (if you build the rest of the deck around critters, which is one way to do it)
Sarkhan, Fireblood- mana accel and good other effects on the cheap
Breath Weapon- instant speed nuke that doesn't affect you

You could also look into some of the cheaper dragons that are still quite good, such as:
Moonveil Regent
Thunderbreak Regent
Verix Bladewing

Since you're running blue, it would also be quite helpful to add in some tactics cards to help move through the deck more quickly, such as:

Ponder
Preordain
Brainstorm


Just some thoughts.