What is your favorite Class Ability or Spell or Skill or whatever you want to call it, that you enjoy the most for your Class, the coolest one for your Class to you?
(Choose only 1.)
(Not the one you use the most because of it’s the most efficient or has little or no cooldown, but the one you think is the coolest, that is your favorite of them all for your Class.)
(Not an item or trinket or whatever like that.)
As an example, for this Class my favorite Class Ability is Vanish.
Windfury by far
Conflagrate! It is a talent not many warlocks have. It consumes a spell (immolate) to provide an instant hard hitting nuke.
It is inline with what warlocks are about imo, give up something to gain something else.
Cold Blood
cus i enjoy watching the snow flowers
Alterac Valley Snowball 
what exactly are u giving up though when it’s a dps gain and has no need to be optimized in some way
Shield wall, because it saves my life when healers are sleeping.
My favorite feature of the warrior class are stances, all 3 of them and the concept of stance-dancing in general, I really missed it in retail
Aimed shot hitting on rogues who think their evasion is going to help them and get critted by 2k crits ohh soo wet
Oh and also flare. Rogues who think their vanish is going to help by standing on a flare and waste their CDs xD
Death coil… because screw you, i win!
6k execute crits 
As a pally: Exorcism hitting HARD on Undeads and Demons.
sheep/counterspell/iceblock
Fear.
It is the most fun to use. Apart from easy one sided kills on targets I should of never been able to kill… it has given some of the funniest moments in my gaming experience.
Fearing someone that has ran into a doorway into a pack of mobs.
Fearing someone on a mount and seeing them fear across the map picking up every mob in town.
Me and my mate over pulling and just as we have one mob left I fear it to allow him to give one last heal to us both… and it runs into that one pack in that one direction. Haha.
Good times fear, never be nerfed.
Blessing of sacrifice
Its fun to use in all kinds of scenario’s but its most fun when fighting in wsg, and they try to crowdcontrol you with blind / polymorphs and it keeps breaking immediatly due to your sacrifice target beeing under attack
Unironically Bubble.
An OP ability that gives you 12 seconds no matter what. You could be in a middle of two enemy raids and still have the time to sapper/run/dance with the enemies.
Close second for me is Shadowmeld.
Stormstrike.
Oh, first hit didn’t proc WF? well have another!
Feral charge. Roots and interrupts casts. Also exceptional for saving chainlightning cloth wearing shamans that start off a pull with casting a elemental master+CL+shock that overtakes you as you engage a pack. And ofc to escape a sticky situation by charging a critter or a mob/other player then popping travel form.
Stealth, I’ve been able to gather thousands of gold because of it. Also being able to lurk around spying on people is fun.
Edit: I wanted to say ambush because of one/two shotting cloth wearers but stealth is overall the winner.
Obviously, for priests, the answer is mind control.