I honestly don't think ASTs really need this or for that matter more complexity to their gameplay. Further, this probably gives AST too much versatility compared to the other two healing classes. Even with a CD on it or a mana cost it would potentially add power that puts them above the other two healers.

Personally if they give AST any major changes I would want to see them make the card system be a little bit more reliable and more about strategy than just pure luck. Or at the very least make the cards that have little value now be a bit more useful.