Invisibility spell

This spell could help in attacking by creating an area splash for the troops inside to become invisible for a short time while on the inside while still being able to shoot from the inside this spell is unlocked at townhall 10 the lvls are listed below sorry about hard to read stats
level/ Invisibility time/ Cost/ Creating time
1/ 3 seconds/ 28k elixir/ 45 minutes
2/ 3.5 seconds/ 29k elixir/ 45 minutes
3/ 4 seconds/ 30k elixir/ 45 minutes
4/ 4.5 seconds/ 32k elixir/ 45 minutes
5/ 5 seconds/ 34k elixir/ 45 minutes

There have been several threads on this already, but the main problem are hogs. I'll let you figure it out for yourself.

This was ruled out

Spell Related: New spell ideas: * (VISION) Invisibility, smoke screen, shroud