Bloodlust

Bloodlust is by far the ultimate spell for a shaman. For less than 1,000 mana, at an instant cast no less, the shaman can increase the melee and ranged attack speed, as well as reduce the casting time, of EVERYONE in their party by 30%. For 40 seconds. That's just insane. You can kill a 5 man boss in less than 40 seconds.

This spell can take Lightning Bolt's cast time down to 1.4 seconds (if you're Elemental, of course). Chain lightning goes down to 1 second.

Not to mention the lore and love behind the spell. This spell has been a staple to Warcraft games since Warcraft II. I myself am overjoyed to see it finally implemented. I feel like a real shaman, now.

Why it shall always be Bloodlust:

Warrior: Help me, I'm hurt!
Priest: Not to worry dear, feel the grace of the light! I shall heal your wounds...*le healz*
Shaman: *Bloodlust*
Priest: BLAAAAAAAAAARGH I'M SO FREAKING ANGRY! YOU AIN'T DYING ON ME, WEAKSAUCE-IN-A-CAN!
Shaman: RAWWWWWWRRGGHH
Warrior: WEAKSAUCE? IF I DIDN'T HAVE TO STARE AT THIS CROTCH, I'D KICK YOUR DRESS-WEARING !@#!
Boss: Take my loot! All of it! Just please stop yelling! Making the yelling stop, mommy! /fetalposition

Warrior: Help me, I'm hurt!
Priest: Not to worry dear, feel the grace of the light! I shall heal your wounds...*le healz*
Shaman: *Heroism*
Priest: Awwwww yeah! Hero time! Heal your own damn self, I have evil to smite!
Warrior: Wait, wha-*smooshed*
Shaman: /cast Astral Recall
Boss: Eww, I just stepped in gnome warrior...

An amazing change in Wrath of the Lich king has come to Bloodlust. It now affects the entire raid.