Lightning Spell at Town Hall 17: max level 12. At Town Hall 18 the cap is level 13. It unlocks at Town Hall 5. Max level per Town Hall: TH5 4, TH6 4, TH7 4, TH8 5, TH9 6, TH10 7, TH11 8, TH12 9, TH13 9, TH14 9, TH15 10, TH16 11, TH17 12, TH18 13.
Tap a Town Hall to open this item there. Dashed: not available at that Town Hall yet.