I would encourage you to post your roster, and the builds for the champs you took into Hydra, and we can see if we can help.
It took me some practice and building, and it can be very frustrating, but I have learned to do okay on both hard and normal and am willing to look and try and help, at least.
Here's my Normal key from this week....
There are certain mechanics that every head uses and if you find it interesting to "study" those mechanics and find a way to counter them with what you got in your roster, then Hydra is fine. If not, well there's other content to venture in and have fun. The rewards are not crazy and they alone cannot motivate the majority to participate. Although I'll be more than happy to get Mithrala in my roster and I built a stone skin set for my Cardinal who rocks tag arena ever since I hit Hydra because I enjoy the thrill of having a good fight and a great result (at least for my standards).