I'd make Herc's grip on the sword/club a little tighter, more forthright. Also, on the hydra heads, where the mouth corners are placed, with a flattish area of large scales behind it, make it look like the jaw hinge is placed halfway along the jaw. But in real-life reptiles, from
snakes to
crocs, see how the corner and the hinge go right the way back.
But otherwise, very nice; and seeing as this topic's three months old already, que sera, sera.