When you like and follow this game on facebook and twitter, It would be nice if the shields applied across all campaigns, as of now they only apply to the campaign you went to the links from.
That horrible feeling when your 2-1 on level 15 with 15 seconds left and you go to grab the last invincibility powerup you need to win and kill that Raze soldier with full health . . . and your ally drops in from nowhere, steals it, and proceeds to run around in circles while raze slaughters you.