Viral Drake

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Lotus Guardian

Chromium

Flying
Rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)
At the beginning of your upkeep, sacrifice Chromium unless you pay {W}{U}{B}.

Tempest Drake

Peregrine Drake

Flying
When Peregrine Drake enters, untap up to five lands.

Catacomb Dragon

Flying
Whenever Catacomb Dragon becomes blocked by a nonartifact, non-Dragon creature, that creature gets -X/-0 until end of turn, where X is half the creature's power, rounded down.

Alabaster Dragon

Flying
When Alabaster Dragon dies, shuffle it into its owner's library.

Rakdos Drake

Flying
Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)

Pendrell Drake

Flying
Cycling {2} ({2}, Discard this card: Draw a card.)

Silver Drake

Flying
When Silver Drake enters, return a white or blue creature you control to its owner's hand.

Teeka's Dragon

Flying; trample; rampage 4 (Whenever this creature becomes blocked, it gets +4/+4 until end of turn for each creature blocking it beyond the first.)

Lightning Dragon

Flying
Echo {2}{R}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
{R}: Lightning Dragon gets +1/+0 until end of turn.

Palladia-Mors

Flying, trample
At the beginning of your upkeep, sacrifice Palladia-Mors unless you pay {R}{G}{W}.

Wind Drake

Mist Dragon

{0}: Mist Dragon gains flying. (This effect lasts indefinitely.)
{0}: Mist Dragon loses flying. (This effect lasts indefinitely.)
{3}{U}{U}: Mist Dragon phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before you untap during your next untap step.)

Shrieking Drake

Flying
When Shrieking Drake enters, return a creature you control to its owner's hand.

Covetous Dragon

Flying
When you control no artifacts, sacrifice Covetous Dragon.

Iridescent Drake

Flying
When Iridescent Drake enters, put target Aura card from a graveyard onto the battlefield under your control attached to Iridescent Drake.

getting more of

Azure Drake

Shivan Dragon

Flying
{R}: This creature gets +1/+0 until end of turn.

Nicol Bolas

Flying
At the beginning of your upkeep, sacrifice Nicol Bolas unless you pay {U}{B}{R}.
Whenever Nicol Bolas deals damage to an opponent, that player discards their hand.

Clockwork Dragon

Flying
Clockwork Dragon enters with six +1/+1 counters on it.
Whenever Clockwork Dragon attacks or blocks, remove a +1/+1 counter from it at end of combat.
{3}: Put a +1/+1 counter on Clockwork Dragon.

Moonveil Dragon

Flying
{R}: Each creature you control gets +1/+0 until end of turn.

Ebon Dragon

Flying
When Ebon Dragon enters, you may have target opponent discard a card.

Black Dragon

Flying
Acid Breath — When Black Dragon enters, target creature an opponent controls gets -3/-3 until end of turn.