I'm about to begin the final mission for the 1st time, I've got the usual warning about making sure I've played things before embarking on the finale as some content will not be available after.

What exactly are we talking about here? Missions that are unlocked via power? I assume all the war room quests will still be active? Do I not get new ones once I'm in post-game?

@flstyle: From everything I've gathered you should have full access to all the areas to clean up sidequests as you see fit.

You can do everything but companion quests.

@corevi: @demoskinos: Thanks!