Limit Break is cool, but what if we had Dual/Triple Techs?

[Zenza]

...

If they ever make a Mime job, as impossible as that sounds to balance, their Dual Tech could be taking the shape of the targeted party member, doing a big arena-wide effect appropriate to the partner, and then slip back into their original form without ever taking control away from the targeted party member. Tank partners get the generated aggro.

For other hybrids, you could take a few approaches:
Granting temporary invincibility is obvious, but exploitable. Development has been understandably reluctant to use it.
Providing a hotkey or specific controller input to confirm activation of a Dual Tech, once a hybrid approaches you and activates his own ability. This is a bit clunky.
Ensure that the participating team member retains full mobility while executing the Dual Tech. Possibly integrate that into the ability itself, like "everyone I run by gets healed with radiating pulses of holiness". The problem here is that it still takes away player agency regarding what he can do - even if his attacks in the Dual Tech are stronger, he might have needed that time to stun or silence an enemy!

It's definitely a tricky problem.