Thunder Chicken

Strategy
This can be soloed by a meleer with almost max melee defense (513 with beers is adequate) and 400+ life, but is much easier with support. The Thunder Chicken does typeless melee damage, so the 80+ Olthoi Armor and a Greater Olthoi Shield work well. A major storm ward will help against the initial lightning war magic.

Send the meleer in to kill the small spawns until the Thunder Chicken appears. When it does, retreat in circles and heal, keeping the shield toward the chicken, until it runs out of mana and stops casting wars. Then kill the little chickens and push the Thunder Chicken into a corner opposite the door. With the Thunder Chicken backed into the corner, you'll only get hit about 1/5 of the time -- the rest it will try to back up to attack. If you stay like this, eventually it will try to run back to the spawn point and then teleport back, so you need to get its attention. Attack for a while (with a fire rend or something with a good melee def bonus), push it into the corner and see if it wants to reset.

Once it's not going to reset, it's time to debuff the Thunder Chicken. Push it into the corner, equip your Royal Runed Baton, and use that to cast Futility. Even with 450 spellcraft this will take several tries. Be sure to heal between attempts, because you'll get hit hard. Switch to a good melee d wand and cast imperil and fire vuln. There's no need to fester, since this has an extremely low regen rate. Attack with an AR fire weapon.

If you have support, send in the others when you are ready to debuff. Have them heal the meleer from the opposite corner while he casts. If the meleer dies, they might have enough time to portal recall without dying. Once debuffed, any healers should stay in that corner, and anyone who wants to attack should go up to the Thunder Chicken so that it doesn't get loose.

A brave mage can also debuff the chicken while the meleers keep its attention.

Lore & Dialog
You give Master Arbitrator Egg. The Arbitrator looks confused for a second and then nods his head in apparent understanding. Master Arbitrator tells you, "You now have access to the Chicken Arena." Thunder Chicken blasts you for 267 points with Lightning Bomb. The thunder of Thunder Chicken crushing  is followed by the deafening silence of death! Squakzzzt!!! Squakzzzt!!!

Thunder Chicken's seared corpse smolders before you! Bgaaaaaaaaawww...k

You give Master Arbitrator Thunder Chicken Token. You've earned 10,000,000 experience. Master Arbitrator tells you, "I see that you have proved you [sic] skill against the Thunder Chicken. Well done." Master Arbitrator tells you, "You shall be known to all as the "Thunder Chicken Slayer"."