Ask about Healer's "Targeting Skill"

I choose Healer to start playing this game. After 1 week, I reach 105 lvl.
But I have a problem with mastery "Targeting" in Martial Art table. I don't know how to use it or can it work automaticaly?
I pull skill (After use 9 mastery point to learn it) to quick using bar, and then target a monster, then press skill. Nothing is happened.

 

thank you

 

It's not ment for a monster.
Like it says to increase damage of the target for 15 sec.
It's a buff that gives a higher damage increase.. That it.
NOthing special, but it can be nice if u find a way to work with it

 

First of all, u need to be in a party with someone so u can use that skill on the monster/boss the same as leech buff!

Targeting - its a buff who gives you extra dmg to "targeted monster"!