I actually have never used the "!" method for this but it seems shorter and more elegant. If it is causing problems, you can always use the [stance:0] or [form:0] version instead. I haven't had any problem with those.
Originally Posted by Sifonology
For that purpose I use a [@mouseover] macro and just hover quickly over each boss frame. I actually tend to use [@mouseover] on all my instant cast spell macros.
Originally Posted by icecoldsir
I'm not at my wow computer right now but if memory serves, this is roughly the macro that I personally use:
#showtooltip [mod:alt]metamorphosis: doom; corruption
/cast [mod:alt, stance:0] metamorphosis
/cast [@mouseover,harm,nodead]  corruption