New spell! The invisibility spell! [Idea]

[mega9yo]

Name: Invisibility spell
Training Cost: 30,000 elixir
Targets: Troops
Effect Type: Invisibility
Damage Type/amount: Increase by 12.5% to start off with.
Training Time: 60 min
Description: Invisibility lasts 5 seconds to start off with.
Research/Spell levels: LVL 2: 18.75% damage increase and 7.5 seconds long, LVL 3 25% damage increase and 10 seconds long, etc.
Lab level: 8