The easiest thing to do would be to use an existing stat file that has the ability you need.
So on a character you have placed that's set to player in the side bar, go down to the Stats entry. I suggest using the arena stat entries for testing. When you click the stats bar a little search bar will show up, just type arena in there and one of them probably fits unless you're trying to make a super high end skill.
If none of them obviously work (wizard, ranger , whatever) then you can make your own stat entry really quick in the stats editor. If you need help with the stats editor I can probably point you in the right direction but that's not my best area.