I actually prefer the original double attack mechanic.
Perhaps it comes back with full attack = original attack x 2^n?
N=number of times it died.
This way no attack buffs are carried over.
Or you could keep the attack buffs and raise the initial cost.
. . . You have no problem with the fact that there is literally no way to kill it? It's better than Schrodinger's Cat!!!
Killing is not the only method to counter a card.
I do feel that the cost will have to be adjusted to account for the greater immortality but I still feel the original effect is more creative and more thematically appropriate for a hydra card.
Thus I feel that it is worth the time and effort to balance the original effect.
@Emerald Tiger
Hydra suggestions keep coming because it is a famous creature and each previous version "did it wrong". Remember the name is the least important part of a card (IMHO).
True. This is the best representations of Hydra I have seen thus far, and it's not a copy of a card in the Armory, so I guess it's a good card.
In my opinion, it needs a bigger cost (to avoid fractal+this or pandemonium+this+water mark or Fractal+Pandemonium+this O.o), and an ability tweak. Attacking 2x times each time it revives sounds ok, and doubling the original stats sounds better, but it's up to you whether you take it or leave it.