One thing to remember about Galek - the passive has a 4-turn cooldown. I'm not really seeing him being a monster in Hydra as a result. I think he fills basically the same role Ninja does. The passive acts as the cooldown-reducing A3 that Ninja has, and the A3 does the HPburn-part of the A2 from Ninja. The ATK up on his A2 is largely irrelevant, I think. The only big thing is the block buffs part - so I'll give you that he'll fill the role better than Ninja, an open up a bit more design space for the team, but I don't see him as being a big gamechanger here.
Speed tuning, Relentless, etc.
Galek looks like he's going to be markedly better in important difficulties in Hydra than Ninja and if the passive is the only thing we're picking at, then that says a lot about just how good he is. I see him being an absolute monster in the high turn count comps which are 100% going to be relevant for Brutal/NM now, and UNM later.
The A2 looks like a tremendous way to blast through damage and fast. It being random seems beneficial versus Mischief, too. I think you're underselling the A3 speed down, even if it's conditional. That kit is sweet. :)