Dale is a goblin mechanic who works in his inventions in his own gigantic garage. The garage has very high ceilings (easier to test explosives!). It is rectangular, with the garage doors on either short end, and the long walls lined with a variety of engines, each with giant exhaust pipes sticking into the room.
Listen, it doesn't have to make sense. Just roll with it.
Equidistant from the doors and each other are two large square metal plates on the floor. These plates are actually the tops of big hydraulic lifts (like what your mechanic uses to lift your car in the air so he can work under it more easily). The one closer to your entrance starts level with the ground, and contains a few gun turrets in various states of repair. The other one is a few feet off the ground, and holds a tank. The kind with armor and treads and cannons. Under that platform is Dale, working away on the tank. Since he's working on it, one of the treads has been removed and the tank will remain stuck on the lift for the entirety of the fight.
When Dale sees your raid enter, he puts on a gas mask and mounts two fans on his shoulders. He pulls out a remote control and hits a button, starting all of the engines along the walls. This fight has a built-in soft timer. There is no ventilation in the garage, so as the engines spit exhaust, the room slowly fills with exhaust. The exhaust puts a stacking debuff on everyone in the room, reducing max hp by 5% percent per stack and damage dealt by 20% (always 20% no matter how many stacks). A stack is added every 30 seconds. Eventually, your healers won't be able to keep the main tank or raid alive, but a better-geared or more-skilled raid will survive this longer (kind of like Gruul's growths). The stacking debuff also does a small amount of damage per stack. This ticks every 8 seconds (meaning you can fully bandage in between ticks, which is important).
Starting the engines begins phase 1.
Phase 1: On the ground.
Dale's fans blow the exhaust away from him, shielding him from the debuff. The fans are not strong enough to blow a player away. So the main tank and the melee get close to the boss. This puts a second debuff on them that negates the damage and the dps reduction from the exhaust (not the HP reduction) while they are in range of the boss. So there is an advantage to being in melee range of the boss.
However, the boss keeps laying down time bombs, forcing the tank to move him. Thus, it's not a good idea to keep your ranged dps or healers in melee range of the boss, since the constant movement will make them ineffective. Instead, they can stand still at range and eat the dot tick. At the same time, however, they'll have to deal with the engine exhaust pipes themselves.
These bombs also create their own smoke, which stacks with the exhaust. Every bomb that explodes unimpeded will add another stack to the exhaust! This could get out of control very quickly, which is why your offtank will have to throw himself on top of every bomb! Take one for the team! The bomb itself will be a large, flashing object. Mousing over it will give you the interaction "gear" symbol. Just right click it to throw your body over it and protect the group! A tank will be able to weather the bomb damage with heals. It's like tanking adds!
Every 20 seconds, a third of the pipes (selected randomly each time) will let out small streams of pre-exhaust, and the corresponding engine will expand visibly. A few seconds later, a jet of black smoke will blast out from these pipes. Unless you are in Dale's melee "fan bubble" of protection, being in the smoke jet will reduce your chance to hit and effectiveness of your heals by 75% and cause a few ticks of noticeable, but not necessarily deadly, damage. Thus the best strategy for the ranged and healers will be to move out of the way of these pipes when they are about to blow, to avoid the smoke. However, making a mistake and getting stuck in the smoke doesn't kill you, it just reduces your effectiveness and basically takes you out of the fight for a moment. It leaves plenty of opportunity to practice and learn during the fight, rather than dying early on and never learning how to do it (coughThaddiuscough).
This makes it the melee "burn phase", since the dps of the ranged is hampered.
And that's the first phase. Tank keeps moving the boss, melee chases him, and ranged/healers avoid smoke blasts from the engines.
Phase 2: The lifts
Every minute and 30 seconds, Dale will super-power his fans, blowing the melee out of range. He'll run to his tank and activate the hydraulic lifts. Your raid has a limited amount of time to get on the other lift (the one with the gun turrets). Both lifts will extend high into the air, leaving anyone who doesn't make it to the lift out of the fight for about a minute. They will be out of healer range, and have to rely on their own class abilities, potions, and bandages to stay alive. So a mistake here doesn't kill you, but it does reduce your ability to contribute to the group.
Oh, and by the way, don't fall off the lift. That will probably kill you.
When the lifts hit the top, Dale will emote that he is activating his Invincible Death Machine. A visible electric forcefield will appear around his tank, and he will begin firing upon your group as well as dropping bombs down onto the ground below (if you miss the lift, you can avoid these if you are paying attention). He'll basically be lobbing aoe missiles that nail one person hard at random, but do an aoe that hits everyone on the platform for minor damage. This will be a phase where aoe healing shines, while phase 1 is more focused on traditional tank healing with minor raid healing. He will be close enough for ranged dps to attack him. Also, the exhaust doesn't reach this high, so the debuff isn't a factor for this phase.
Your tank and any other melee climb into the turrets. They act as vehicles and regenerate their max 100 energy at a rate of 10 energy per second. Each has 3 abilities:
1) EMP grenade. 30 sec. cooldown. Costs 60 energy.
2) Anti-missile flares. 20 sec. cooldown. Costs 40 energy.
3) Machine-gun with no cooldown. Costs 20 energy
The EMP can deactivate his shield for 20 seconds, allowing the ranged dps to unload on him (this is their "burn phase"). The flares can decrease incoming damage to the raid to give the healers a break (stronger groups can forego these for greater turret machine gun dps). Since the EMP only works for 20 seconds but has a 30 second cooldown, the players on the turrets will have to trade off EMPs to keep the shield down. You can't just rely on one player on one turret to take care of it.
After a minute of this, the platforms retract to the ground, the turrets deactivate (and kick players off them), and phase 1 resumes as normal for 1:30. Rinse/repeat.
Variable rewards for variable difficulty:
Dale's tool chest contains the loot, but can only be opened once he's dead. However, the exhaust progressively damages the loot. The longer the fight takes, the fewer the number of usable items in his chest. Complete the fight in under 3 minutes in ten man (hard mode), and you get the normal 2 ilevel 200 items, 2 ilevel 213 items the usual 1 token of heroism, plus a bonus heroism token and a bonus valor token. Complete it in under 5 minutes to get a bonus heroism token and a bonus ilevel 213 item beyond the usual. Take over 5 minutes, and you only get the usual 2 ilevel 200 items and a heroism token.
So, what do you think?