We've discussed the conquests before, and I think many are straightforward. Boss mode is often left out and considered to be hard - when it's actually relatively easy and by far the easiest for any well-coordinated group. And in my opinion, it's by far the conquest that's most fun.
Time to KILL a Boss: Estimate your Power
First, we need to understand the relative difficulty of the bosses. There are four bosses that have animations and take a bit longer to kill:
All the other bosses can, at least in theory, be a one-shot. Test how long it takes you to kill Malthael on TX, and after that any of the others (e.g., Azmodan) just to get a feel for how long the boss fights will take you. Can you kill Malthael in less than a minute (including all animations) and Azmodan in less than 15 seconds? Then your DPS should be high enough.
Time to FIND a Boss: Make an Ordered List
Next, we need to look at the difficulty of getting to the bosses. For that, we create an ordered list. The one we used for our run was this:
Basically the list can be split into two halves (top 9, bottom 7). The first 9 take a bit longer, either because the way is so long (Malthael, Siegebreaker) or the pathing can be difficult to find (Izual, Aranae) or both (Urzael, Adria). Also, as aforementioned Malthael, Urzael, and Diablo take a bit longer because of animations and transitions and stuff, so it's good to get those out of the way early (only Belial being on the bottom half).
Gear and Spec Requirements/Advice
In terms of gear/specs, you obviously need great mobility. That means:
Wizards need Teleport and Aether Walker. Also get some arcane power regeneration. You can switch out Aether Walker before the boss fight to some DPS weapon of your choice. Alternatively, you can try Illusionist+Teleport, or even In-Geom, but it won't be as fast at all (and quite dangerous as well).
Witch Doctors are strongly recommended to have Manajuma's set + Angry Chicken. Again, switching to some DPS for the boss. You can also use In-Geom and kill elites on the way to get Spirit Walk up in combination with the Zuni set and lots of pets; it works, I've tried it, but is a lot slower of course. But it's a great synergy with a boss spec (lots of pets) and can be done with the starter set (Zuni) and requires no gear switching.
Demon Hunters have Vault, enough said. Vault alone is crazy, with Danetta's it's a joke. Again, switch weapons out for boss.
Crusaders absolutely need Swiftmount and Steed Charge. Again can be done using In-Geom and then killing elites on the way, but will be significantly slower.
Barbarians don't need anything for running as the Raekor set is great for constantly charging, so they're basically set up from the start to do this. Remember to use Boulder Toss for the bosses!
Monk can be really fast with the Thousand Storms set or Jawbreaker to use Dash, or even In-Geom, but it's not as easy to get there as for other classes I'd say.
Can I Solo It? Yes You Can!
I think for doing this solo, WD is probably best because it has a great mix of mobility and insane boss DPS. But any class can do it. If you're solo, start from the top and keep in mind that the last ones can be done super quickly. You could probably do the bottom 6 in 3 minutes including going there and killing them, so if the first 12 take you 15 minutes you'd still be more than fine! It might take a few tries, but it's absolutely possible.
Group Play - Coordinate and Celebrate
Now to my favorite part: How to get this conquest done super easily - in a group. That's how this was done super early on in the season by some groups, and why I advise some people to try it out. This conquest was completed just 5 hours after the start of the season (by a group of paragon 200 players of ZE).
The preparation is that everyone needs to agree on an order to kill the bosses in, as well as an assignment for the early bosses about which players take which bosses. Depending on if you're 2 players, 3 players, or 4 players, you should have this list either printed out, on your PC, or even best just write it down on a piece of paper and put it next to you:
It's arguable if setting up bosses makes sense for 4 players in round 3; we did it, but you can also just start running together. For 3 players, after Ghom there's no potential to run into dead ends and no super long walks anymore, so you should definitely not split up anymore but just run all together, because setting up bosses takes some time.
Now the reason why this list is so important is because you set up bosses in the group. You do this by putting a Town Portal in front of the boss area, join the others to kill a boss, and then use the MAP (not your town portal spell!) to go back to town, use your town portal to go back to the previous boss you have set up, and then all the others join. Is this confusing? If you think so, let's do a walkthrough of an exemplary Boss Mode run in a full group. The four players are called Adam, Beth, Carol, and Dan.
Adam takes Malthael, Beth goes for Urzael, Carol starts looking for Adria, and Dan searches Diablo.
Dan arrives first and teleports back to town - and waits.
Adam gets to Malthael and teleports back to town - and waits.
Carol finds Adria and teleports back to town, and waits.
Beth finally get to Urzael, starts the teleport - and realizes (by looking at the chat) that all other three players already have found their bosses. She cancels the teleport and just clicks on the boss fight area to start the fight. Everyone accepts, and Urzael is put to rest.
The remaining three bosses are to be tackled in their respective order, which means Malthael is next. Therefore, as soon as Urzael is done dying, Adam presses "m" (NOT "t"!) and clicks on the Enclave to go back to town. There, he clicks on the town portal and everyone joins in to fight Malthael.
After the fight, Carol is next. Again, Carol uses the map and not the town portal to go back to the town hub, and then proceeds to use her town portal to go back to Ruins of Corvus and start the fight with Adria.
Last but not least, Dan does the same afterwards to set up the fight with Diablo. After Diablo is dead and the seemingly endless animation of his death is over, Adam teleports to Silver Spire level 1, Beth goes to Halls of Agony 3, Carol heads to the Aranaea Caverns, and Dan makes a run through the Bridge of Korsik. Round two starts!
The first round will take you 6-7 minutes, and that's totally fine. If you're over 8 minutes, you might consider restarting (though you can still make it). If you're anywhere below 6 minutes, the rest will be a breeze. The first 4 bosses are by far the biggest issues in terms of getting there and time required to kill.
If one player in group has particularly long loading screens, Cydaea is the one boss that has an additional loading screen and might be assigned to someone else.
Some bosses are easier to get to if you can teleport rather than just walk. For example, wizards (teleport) and monk (dashing strike) can just "skip" the small way enclosed by two iron gates on the way to Skeleton King by teleporting across the area. On the other hand, teleport/dash doesn't help a lot on the way to Ghom or Adria because usually doors are closed, making teleporting through walls impossible.
Every class: I strongly recommend to use Homing Pads, and if possible also a spell that increases toughness for the teleport (e.g., Energy Armor - Force Armor, Desert Shroud, Iron Skin, and so on).
On hardcore, you also need a bit more toughness, obviously. That's why HC players tackle this a bit later (in group); if you're only 2 players and on Teamspeak, you can also just establish a rule for an "emergency accept" where you just go into a boss fight if a player absolutely feels like he's not making it out to town. Obviously not dying is more important than success of a conquest.
Good luck everyone! I know this is a lot of text, and I could've probably made it shorter, but I didn't have time for that. But I hope this helps some people.
Notes: Moved Malthael down the list because of new Pandaemonium Fortress 2 waypoint
My favourite part of the example was when Carol was swapped out for Charlie. Maybe She changed her name? Charlie is a unisex name, so perhaps Carol even got a sex change during this boss run.
ROFL... I genuinely laughed (and then facepalmed). As a little bit of backstory, her full name is Caroline Charlene, so not all of her friends call her by the same name. Of course you couldn't know that, so I changed the name to be the same throughout the entire story. ;D
Some answers that are overdue:
@chidoriseanbon: I don't know of any communities. Since it's a one-time thing, I don't think people would make a community for that. But maybe you can make one? Or just create an LFG thread in our LFG forums.
@zikje: I think the set doesn't matter, I'd personally do it with Zuni (because of pets). What matter is more the weapon set, you can do it with any of the other sets (well Jade might be a bit edgy).
@PTXAA: Yeah, it depends how well you know the patterns and how quick you are at checking the four possible exits. We personally never had an issue with it, so in our personal list it's a bit lower. Of course like I said you can change the order as you like, as long as everyone in your group is on the same page.
@cpy: Yes, exactly. It took me hours on Teamspeak to convince my team members to do it, we then got it down first try in 15 minutes or so and that was with one of us disconnecting, so we had to wait 2-3 minutes with the first boss encounter. Ended up rank #17, I believe. Could've easily gotten top 10 if only some of my team members wouldn't have been so reluctant to give it a try It was way easier for us than "Curses!", which took us two attempts.
@Shapookya: Yeah, kind of. Although I've heard people say (including in this thread) that they found it ridiculously easy solo as well. But once you know the strategy. it's almost impossible to fail this as a group after a certain power level. I think any group of paragon 400+ players should one-shot this even if they mess up a lot of things.
@Alandrielir: Nope, everyone needs to kill all bosses. If you miss one boss fight you don't get credit for the kill, you need to be in the area, i.e., accept the fight.