About theme, lets see. Wikipedia: Jinn (
http://en.wikipedia.org/wiki/Jinn).
Djinns are surely related to fire, but also can be related to other elements:
Aether: "are supernatural creatures in Arab folklore and Islamic teachings which occupy a parallel world to that of mankind."; "described them as creatures of different forms; some resembling vultures and snakes, others tall men in white garb.[13] They may even appear as dragons, onagers, or a number of other animals."
Air: "divide jinn into three classes: those who have wings and fly in the air, (...) and those who travel about ceaselessly."; "Jinn have the power to travel large distances at extreme speeds and are thought to live in remote areas, mountains, seas, trees, and the air"
Death: "also claimed that the jinn may subsist on bones, which will grow flesh again as soon as they touch them, and that their animals may live on dung"
Darkness: "the jinn account for much of the "magic" perceived by humans, cooperating with magicians to lift items in the air unseen, delivering hidden truths to fortune tellers, and mimicking the voices of deceased humans during seances.[17]"
I think that living at a parallel world and being able to change form would be enough to relate them to aether. If they have something to do with lightning, well, they have supernatural powers, so I guess they could produce lightnings.
About name, I have chosed Djinn because its better known. There are some classes of djinns, however: "the šayṭān, the ġūl, the mārid, the ʿifrīt, and the ǧinn". Efreet is also a name some people could know, but I wasnt wanting to use, to let another idea open to Fire. Something alike "Elite Djinn" (lol), or "Djinn Sage", etc, could work?
About how powerful the card is... I really dont think create some Lightnings would make it that powerful about killing the opponent. A lot of cheaper creatures do much more damage, charger, for example, also ignores shields and can do more damage than a lightning at no cost once the card is played. Lightnings can be more useful vs sundials or some shields (considering other creatures), but it isnt this so high advantage. Lightning more powerful that Fire Bolt? Once you have 10 fire quanta, its not. I thought about creating Fire Bolts, but this would be OP, once a Fire Bolt can do 20+ damage in late game. In fact, Djinn would be a powerful card to add CC.
Some chances: I will adjust the maximum djinn HP to 6, and create a 2HP loss every time you use the skill. This is going to make possible for Djinn conceding you 3 "wishes" only, and that fits the theme
Im also thinking about if he could give you "generic" wishes, like creating a random spell from Aether or your mark element. It would lose the focus, and so could have stronger stats, but dunno if its a good idea. Any thoughts?