It's one of GS's 79lvl skills..

Greatly decreases your own skill cast speed but there is a chance that you will consume MP when struck. An equipped bow is required to use this skill.

WTF does this thing do in pvp.... ?
Like somedody will go to mommy crying because that GS bastard "ate" him some MP ..

Well it's simple. It decreases c.speed and when you are attacked it has a chance to suck mana out of the victim. Also check Counter Mind: When attacked, recovers MP with a certain chance. An equipped bow is required to use this skill.
When you're attacked you will recover mana... Wow what great skills for pvp...... They're orienting pr for pve exclusively...

It's just like NcSoft wants to tell us: "Hey there stop arguing in HE vs PR topics because we aim to keep the PR as the PvE archer of the bunch and PvP is of second priority for them"

you are wrong sr is the best archer and with the counter rapid shot and counter dash he got the best skills for archers of ct1 , Counter Rapid Shot - Chance to increase party member's A.Speed of bows + 15 % when attacked. The effect will appear on buff slot besides the buff itself. Effect duration 1 min.
and u can have both counter rapid shot and rapid shot and rapid fire on , u can get to 1,1k atk.spd with sr , thats just omg + fulllbuffs 1/2 shots will be criticals in ct1 sr becomed the best archer for pvp (pve too)

i think they were being sarcastic about that .
and yea, thats what the skill does ho heres s an easiser explanation - counter skill to nerf pr in pvp

First mages nerfed, than glads and tyrants owerpowered, ability to ewade skills.. And now what? Is ncsoft is going insane?? Whats next? Catapults, balistas, own boats and planes? No balance at all.. I think i gonna quit l2 >.<

hm... one less buffslot to use then... then PR can do 1 more buff outa there
( trying to make cons sound as pros )