If you cast this on your followers, they will become invisible for the 2 minute duration of the spell. This spell will broken if your unit attacks any of the enemy tribesmen or their buildings.

You can track invisible enemy units by closely watching the footsteps they leave on the ground.

 

Note that this spell does not affect your shaman. 

Invisible followers can still be converted by enemy preachers, even though the enemy can't see what they're converting.

Also, angel of deaths can see invisible units and atack them.

 

In online gaming, be careful not to confund your own invisible units to ghosts - they are alike!

 

Invisible is such a strong spell that people stopped to play with it online - it can cause devastating damage and has not many counters.

 

In offline gaming, you should really use this spell - invisible preachers can be deadly! You will unlock this spell on level 7, and you can only have a maximum of 4 charges of it.