Polukranos Reborn/Polukranos, Engine of Ruin Hydras never die Polukranos Reborn is a three-mana Green 4/5 with reach, so it can block flying creatures
The otter can replace the second copy of Expansion, giving us some redundancy if we need to use some Expansions on earlier turns (often to turn a counterspell or Duress back at the caster)
These are all very fun Dragons to run in your decks, and Im not sure that any of them are anything short of super fun
Theres nothing like activating four Arclight Phoenixes out of your graveyard on turn 3 thanks to this bad boy, and even though I only did that once, the memory will still last a lifetime
It's also better in duels
You'll want to increase your Dragon count to ensure that happens with each foe, and note that this is just once per attack no matter how many attack