The card "Healing Burst" Is not healing everyone. When you select it, it brings up the option to select a target. I have tried selecting an ally and target self and the card is only healing the selected target. I've tried this card several times picking different targets and each time it only heals the one person.
Ahhhhh. Well I just joined the beta last week and I don't think I read about grey cards. So thanks I also wanted to note that it also heals the target for 4, not 3 and it's range is the entire map. Now that I know about grey cards this might just be a generic card feature, but rather report what I found than assume things.