assist current target.

If you played wow you would know what this is..

If not, it makes you select the target of your current target.

Example

A is your friend and B is a monster. A has currently targeted B and started attacking. You wanted to help A but you're having trouble clicking B.
So you click on A and press this ability, then you'll get to target B

Thats good, didnt know that myself, made more sense when it was in wow as just pressing T though tbh.

thanks dude ive never uesed it im gonna give it ago when the update is done