I didn't even realize there was an AOE version of 703 til you asked the question.... I haven't used it at all since I was able to reliably get warding margins high enough that 706 would easily stun things for more then 15 seconds. Then I got enough mana to regularly use 711, which will inflict RT as well as damaging.

To answer your question, though, if there were more critters in the room then you can affect with the AOE version and you wanted to ensure a specific one was hit, the targeted version would be preferable.... of course, 410, 435, 709, open 720, or stepping out of the room would all likely be even better options in that situation.


Starchitin, the OG

A severed gnomish hand crawls in on its fingertips and makes a rude gesture before quickly decaying and rotting into dust. A gust of wind quickly scatters the dust.

I always cast 703 open.

There are some casters, like with major ewave or other nastiness, that I will 703 immediately. An open 703 will catch others in the room too who might also have spells. (Dhu goleras and shrickhen are two that come to mind).

I also sometimes cast after my disabler/RT inducer (709, 410, etc) just to keep them from casting once they stand up.

To your question, though... I can't think of any use for a single target 703. AFAIK the extra targets are free.