Hi,
I was working on my AST yesterday and I came up with something:
/ac play <t>
/assist <t>
/assist <t>
/micon play
With this macro I got a good way to use play to throw the card on whatever member of my team and then the macro will switch target to anyone he is targeting (whatever mob or boss) and then change the targeting again to whoever the mob is targeting (the tank, if he's got aggro). The chang occurs instantly and you get to keep healing...
In my tests I saw it not happen once or twice, maybe if you have a high ping it might have some issues. Usually I wouldn't recomend this kind of macro on high end content, since you can't queue Play, but there's a video going on the forums of a Noct Astro solo healing high end content, and he uses macro targeting all the DPS...
Also I have another macro /ac Gravity <tt> and it works best for me. Again I don't recomend to macro spammable actions because of queueing problems, but it work for me...
If someone can test and add some feedback I'd appreciate.