From WoWWiki

Arcane Shot
Arcane Shot Instant Cast 5-35 yds range Y Mana An instant shot that causes [RAP * 0.15 + X] Arcane damage. (Also dispels one magic buff after rank 6)
Usable By
Class	Hunter
Properties
Type	Offensive
School	Arcane
Cooldown	6 sec
Talents
Improvement Talents	Hawk Eye, Efficiency, Lethal Shots, Mortal Shots, Improved Arcane Shot
Other Information
Ranks	9
Requirements	Requires Ranged Weapon

I can shoot you AND read a book.

Arcane Shot is an instant shot that causes 15% of your RAP + X arcane damage.

Contents 1 Rank Table 2 Notes 3 Tips and tactics 4 Past changes

Rank Table

Rank	Mana Cost	Damage	Level	Cost
1	25	15	6	1
2	35	23	12	6
3	50	36	20	22
4	80	65	28	80
5	105	91	36	1 40
6	135	125	44	2 34
7	160	158	52	4
8	190	200	60	5
9	230	273	69	17

Notes

Arcane shot isn't as efficient as Steady Shot, but its instant cast speed makes it useful when it comes to burst damage. It is very useful in PvP and for kiting.

• Damage Formula: [ RAP * 0.15 + X ]
• Arcane Shot deals arcane damage which is bypasses armor, but can be partially resisted.
• Though it deals magic damage, Arcane Shot is not considered a spell and gains no benefit from +spell damage, spell hit, or spell crit.

Tips and tactics

During long fights, Arcane Shot's mana inefficiency can make it a less attractive ability. However, that doesn't make it useless. Working in a few shots, especially in fights that end before mana becomes an issue, can boost your dps.

Arcane shot can be very powerful in PvP. Mobility is the key in PvP, especially for ranged classes, and the burst nature of this shot is also welcome. This is an often overlooked fact because arcane shot deals arcane damage, which bypasses the heavy armor of Warriors and Paladins.

Nothing is better for kiting than rank 1 Arcane shots. Using a lower level ability allows you to negate the problem of mana inefficiency, and while you won't be doing much damage, that's not the point of kiting. Turn on Aspect of the Cheetah, maybe throw down a trap or two, perhaps even slap on rank 1 Serpent Sting and you should be good to go.

You may also want to consider using Rank 6 Arcane Shot as it will save you up to 58% more mana than the Rank 9 one. You will deal significantly less damage but you will still be able to dispel magic buffs, making this more mana efficient in PvP.

Past changes

• Patch 2.0.1 (12/5/06): Casting lower ranks of Arcane Shot than your maximum rank will now reduce the bonus you receive from attack power.
  
• Patch 2.0.6 (1/23/07): The base damage for Arcane Shot has been reduced by about 9% and the bonus damage from ranged attack power reduced from 20% to 15%
  
• Patch 2.3.0 (11/13/07): Arcane Shot (Ranks 6 and above) now dispel 1 Magic effect in addition to their normal damage.
  

Dispel
Druid	Abolish Poison • Cure Poison • Remove Curse
Hunter	Arcane Shot • Tranquilizing Shot
Mage	Remove Lesser Curse • Spellsteal
Paladin	Cleanse • Purify
Priest	Abolish Disease • Cure Disease • Dispel Magic • Mass Dispel
Shaman	Cure Disease • Cure Poison • Disease Cleansing Totem • Poison Cleansing Totem • Purge
Warlock	Devour Magic (Felhunter) • Dispel Magic (Doomguard) • Spellstone
Warrior	Shield Slam

Hunter Attacks
Ranged	Aimed Shot (talent) • Arcane Shot • Auto Shot • Concussive Shot • Distracting Shot • Multi-Shot • Scatter Shot (talent) • Steady Shot • Tranquilizing Shot • Volley
Melee	Counterattack (talent) • Disengage • Mongoose Bite • Raptor Strike • Wing Clip

Classes • Hunter • Hunter Abilities • Hunter Talents • Hunter Tactics