Being a fan of dragons and all things dragon-related, I would like to congratulate you profusely on the accomplishment in this piece. You managed to completely ignore and cast aside some rules of drawing dragons that most fantasy artists would consider unbreakable, and you managed to do it without sacrificing style and botching the piece completely. I am by no means a master artist, but I feel I must congratulate on what I consider to be a job well done and that very few artists could pull off with this level of success.
I think I have seen over 100 hydras in art before. Many of them "scary". This is the first time I've ever had to look away, and actually had a guttural fear reaction to any kind of art. Truly terrifying, David. A new favorite, and new favorite artist.
This is fantastic and suggestive. If I may attempt a critique - not a technical issue but atmosphere/composition - I do not completely buy the rocky cliffs on the background. They convey a sense of "safety", in some way. Such an encounter will be way much scarier and desperate if it took place in completely open waters, without any hope for any eventual survivor to ever reach mainland.