You have exactly seven level 60s. That's *very* early in the game. Unless you have others you're not showing?
The ones you happen to have chosen to level to 60 are quite solid for dungeons, which is what is letting you get to level 20 on them. But dungeons and Hydra are very, very different. A good milestone for when you should be looking to make Hydra teams is being able to get top chest in at least Nightmare CB. If you're not able to do that yet, then you should be first aiming to build an NM CB team.
You've got some decent pieces for a starter CB team. Do some research on how speed tuning works, and then I'd probably build the following team, with all five champs between 170 and 189 speed:
- Stag Knight (DEF down, ATK down)
- Toragi the Frog (Poisons, Ally Protect)
- Ghrush the Mangler (Leech) - turn off A2/A3
- Lonatharil (despite being unbooked, he'll still contribute a decent amount to damage)
- Ronda
You'll need all five to be at level 60, with full masteries and ascension. All five should be running Warmaster, except Ronda who should be running Giantslayer.