I saw in another thread that you're thinking of replacing the Anvil attack because it isn't very Dragon-like. One of my favorite additions to the Dragon fight from the mod Savage Ender Dragon is the addition of phantoms to the fight – they just really feel like they belong in the End, more than they do in the Overworld even. An attack that spawns a phantom on every player would be very effective.
I saw in another thread that you're thinking of replacing the Anvil attack because it isn't very Dragon-like. One of my favorite additions to the Dragon fight from the mod Savage Ender Dragon is the addition of phantoms to the fight – they just really feel like they belong in the End, more than they do in the Overworld even. An attack that spawns a phantom on every player would be very effective.