ABILITY HELP!

[Genenku]

How do I make an ability that removes an amount of mana and does nothing else. Is there a spell I can use like this or is there a way to make an ability that does nothing.

 

[Ryusei]

Make a new skill based off of 'Battle Shout', set all the fields except for the mana cost to 0, and remove everything in the buff catagory.

All done!