Lightning spells:

• The most common suggestion is for a level 5 attack spell that creates a lightning bolt, implemented as a simple ray. Possibly, it causes an electrical explosion on the first target it hits if cast at Skilled and Expert.
• Alternatively, a spell of lightning bolt could be a melee range spell that deals heavy shock damage.
• Chain lightning is a spell that forks off and hits adjacent targets in a breadth-first search (see here for how it might work). Possibly, the lightning bolts can only chain off at 135 or 180 degree angles (maybe 90, too). Chain lightning can still be reflected, but becomes a straight ray.
• Lightning storm, which causes an electrical explosion centered on every monster in your line of sight (possibly with a decreasing chance of doing so as it gets further from you). Or if this is too overpowered, just strike these monsters with an individual lightning bolt that does not cause an explosion.