Defense ninjas visable but immune

The defense ninjas can usually be killed by blizzard or firestorm before they are able to start their attacks, but often some of them are invincible from the time they spawn, til the time they become invisible and attack your troops.

Pretty sure this is not intended as the reason they wait a little while before attacking is to let you cast a well timed instant spell, or to have your firestorm going right before they spawn.

 

Example: I will have my firestorm going before the 5 ninjas even spawn, and maybe 2-4 will die from it, but for some reason the other 1-3 ninjas are just completely immune and go into attack mode.

This happens maybe 50-75% of the time.