Thunderspark has a 6' radius centered on Ramuh. You can indeed hit 2 targets separated by a distance of 12' if you can move Ramuh between them.
Shiva's Sleepga, Nightmare (despite his animation), Slowga and Lunar Roar : 6' radius centered on the target.
Tidal Roar and Diamand Storm : 10' radius centered on the target.
Astral Flow Blood Pacts : 10' radius centered on the avatar.

The range of our Sleepga is nearly two times smaller than the normal Sleepga. We already need to call Shiva and give the order to BP which takes more time than casting a normal Sleepga but the radius is so mediocre that we can't rely on it at all.
Same thing about Slowga, it's a good BP because, from my results it's a 30% Slow independent of the target's MND but the range is just awful.