Skeleton Spell at Town Hall 15: max level 8. It unlocks at Town Hall 9. Max level per Town Hall: TH9 1, TH10 3, TH11 4, TH12 6, TH13 7, TH14 7, TH15 8, TH16 8, TH17 8, TH18 8.
Tap a Town Hall to open this item there. Dashed: not available at that Town Hall yet.