I had no issues (apart from losing most of my team in the fight, but I won... I won!) with the hydra battle about a month ago playing my swashbuckler character.
Now my privateer tries that battle and this is what happened:
After the ebon head disappeared, the goal to defeat the red, blue and purple heads came up. After I'd defeated them, the message about the ebon head returning displayed, then... nothing. Ebon didn't show on the battle board, couldn't be selected, and didn't do anything. The battle board showed no goals.
Please fix as soon as possible. The hydra is one of the most challenging and fun battles in the game.
I have beaten the Hydra several times with friends and we have not had any problems. This is indeed a tricky and sneaky bug. I do not envy the ones at KingsIsle having to ferret this one out. We know you are trying KingsIsle team, hang in there. Also hang in there Katreeny, keep trying, the odds Have to swing in your favor at some point and you will get a bug free run. Perhaps trying some of Ratbeard's head patting and tummy rubbing?
This quest is really making me want to play less and less. Years playing both wizards and pirates (and paying for all the family members). Sure, your run into hard quest but this is different. Head of snake just sits there and you can't hit it. you get attacked over and over without being able to hit. A second head apears on it's sqaure and attacks you. I have tried over and over this bug should be fixed by now. The fact that is holds up the entire storyline make it worst. Hence gametime dropping.