So fire brings out passion in life forms and more violent/energetic natural events then?
Sounds like red color identity from the MtG trading card game. They tend to attribute electricity to red and red/blue color identities, with red also being closely associated with fire and blue being associated with sky and sea (water and air).
Beyond that, the animated TV series Avatar (the Last Air Bender and the Legend of Korra) considers electricity a purified version of fire.
Going back to the Killerwatt plane, this identifies the following possible runic combinations:
Fire
Fire/Water
Fire/Water/Air
Fire/Air
I'd also like to throw in a couple of combinations involving the chaos rune due to the nature of lightning (wild electricity):
Fire/Chaos
Fire/Water/Chaos
Fire/Water/Air/Chaos
Fire/Air/Chaos
Given its apparent simplicity compared to Abbinah, I'm hesitant to attribute it any combination that adds on to Abbinah's, so we can disregard Fire/Water/Air, Fire/Water/Air/Chaos, and Fire/Air/Chaos.
You've also brought up being hesitant to use fire, smoke, or steam since they don't really evoke thoughts of lightning in people, so I'll also knock out those combinations.
This leaves us with Fire/Chaos and Fire/Water/Chaos. Again appealing to the plane's apparent simplicity, I'd advocate Fire/Chaos over Fire/Water/Chaos. This reinforces the idea that lightning is a derivative of Fire, corroborating Mod Raven's claim that Abbinah's eternal thunderstorms are evidence of the plane's roots in Fire and not just Air.
As already mentioned, it's also possible that Lightning could be attributed to another runic element we don't know of.
27-Sep-2017 12:57:43