New dark spell idea!!!

a new dark spell idea: shield spell( protect troops from the enemy defenses)
Town hall level required: 9
Level 1: 20%protection
Level 2: 30% protection
Level 3: 40% protection
Level 4: 50% protection
Cost: 150 dark elixir
Research cost:
Level 2: 20000 dark elixir ( at town hall level 9)
Level 3: 40000 dark elixir (at town hall level 9)
Level 4: 60000 dark elixir (at town hall level 10)

THIS IS NOT AN ORIGINAL IDEA! I think it's being considered though.next time search before you post.