Archavon is located within Wintergrasp Keep and can be accessed when your faction is in control.

Abilities

1. Rock Shards - he will target one player and throw them. That player just needs to move away from others and can be easily healed.
2. Leap - he will leap randomly, the tank should stay where he is standing because he will come right back.
3. After he leaps there will be a Choking Cloud which you must move out of.
4. Stomp - Every 45 seconds he will stomp the ground dealing 4k damage to everyone and stun them for 2 seconds. During this time he will Impale the player with the highest threat and remove them from the fight for 8 seconds. It's important to have the other tank ready to pick him up!
5. 5 Minute Enrage timer so dps him as fast as you can or he will destroy your raid group.