When resting it recovers strain and it heals if there is less strain than endurance. So if you rest with no strain you can heal by the number of endurance? It just seems to make the Players invincible.. If they keep healing?? Am I missing something?

That's it. As an imperial player I've never found it a problem though. If they're resting then they're not attacking imperial figures or completing their objective(s) so it can be a blessing in disguise.

Also so if you really want to keep them strained up, use subversive tactics as the imp. class deck. Although I've never used it as apparently it's really not fun for the rebels.

1 hour ago, Tirisilex said:

When resting it recovers strain and it heals if there is less strain than endurance

Correct, it recovers strain equal to the Hero's endurance

1 hour ago, Tirisilex said:

So if you rest with no strain you can heal by the number of endurance

Yep, you'd get rid of damage if you had 0 strain

2 major problems if Rebels keep on resting:

they aren't moving forward with objectives (most mission have a timer)

they aren't killing Imperial troops (i.e. they're betting Imp troops can't put out enough damage to undo their healing in 1 round...and sometimes it IS possible)

This is also the biggest reason why people feel Hoth campaign is the most Rebel-friendly one: it's because of the lack of timer and the addition of MHD-19 healing bot so Rebels can just take their sweet time to finish Imp troops off

4 hours ago, Tirisilex said:

It just seems to make the Players invincible.. If they keep healing?? Am I missing something?

The players still need to spend actions on resting. This means they don't move towards their mission goal. Most missions in Imperial Assault have a mission timer after which the rebels automatically lose. If they keep being lazy resters, they will never gonna win their missions.

Note that in the app, resting does not heal damage. That's only in book campaigns.

As many people here have pointed out, most missions do have round limits, so obviously every action spent resting could have been used toward something more productive.

Also, and this may be just a bit spoilery for some mission mechanics (I won't say which or get too into specifics, though)