Warning: this post is made before beta 2 is available, but after we've seen the changelog, so it is based on hypothesis and projected gameplay.

[quote quoting="https://forums.sinsofasolarempire.com/371250"]

Envoy's are no longer passively invulnerable. Instead they have a Diplomatic Immunity ability which will grant them invulnerability for 30 seconds with a cooldown of 120 seconds.

[/quote]

Now I make this comment blind, and I might well retract it once beta 2 is out and I've had time to play test it, but have you considered going halfway backward to the beta 1 model on this?  What I am saying is that perhaps the base immunity time might be increased (so that the passive ability can be useful against enemies in the early game to help with diplomacy...they are an envoy after all), but that the diplomacy techs that previously made them attackable instead auto-reduce the amount of immunity time an envoy has while in your gravity well.  (Having not seen the new diplomacy tree yet, I don't know if they would fit in anywhere.

Now please note, you'd want to have something show up on the id card for YOUR envoy cruisers when they are within an enemy's gravity well that this research completed (and thus the active affect) so that you know the envoy will be immune for less time.

Clearly, if you think 30 seconds is the balanced envoy immunity time, then after doing the research, we'd want it to settle to this value. 

Thoughts?

edit: can't get the quote to work properly; if anyone knows the proper cross-post syntax, send it to me by private messages and I'll edit this to work.