How about a spell of invisibility? I think it would be a great spell to have for hiding your groups from defensive buildings (not including traps). There could be three levels.
Lv.1: lays a ring of invisibility for troops in the ring for 10 sec.
Lv.2: for 15 sec.
Lv.3: for 20 sec. (Available for th9)
Available for th8 because its the only one that doesn't have a spell upgrade.
Upgrade spell factory 1600000
Up to lv.2 800000
Up to lv.3 1500000
Thoughts? Plz tell me good or bad.

