This build utilizes two bugs with the firebirds set that blizzard has decided to leave in the game for Season 6 and have said they will NOT be taking action against accounts that purposefully abuse these bugs. Source: http://us.battle.net/d3/en/forum/topic/20744924301
Firebirds 4 piece Bonus bug: The set reads "Dealing fire damage to the enemies causes them to burn for the same amount of damage over 3 seconds..." but this is not how the set is currently working the bug takes the damage you deal with fire damage and then re-applies your damage bonuses that were already applied to that number. Say you hit 5 Billion with a fire attack the enemy should burn for 5 Billion damage over 3 seconds instead it takes 5 Billion * Damage modifiers over 3 seconds. So hitting 5 Billion results in damage tics in the Trillions. However the trick is with the second part of this bonus that reads "stacking up to 3000% Weapon Damage ... After reaching 3000% damage per second the enemy will ignite burning until they die." Once the enemy is ignited the damage is no longer applied twice. So to make it work you have to do controlled damage to not go over "3000%" (the actual number you must hit under is around 6.3 Billion) damage in one hit. If you hit under "3000%"(6.3B Dmg) in the first hit then the enemy will burn with the damage modifiers applied twice. Then you must wait 3 seconds until the burning stops before hitting them again or the enemy will be ignited. So we use Archon form's fireblast to apply this DoT every 3 seconds.
Firebirds 6 piece Bonus bug: The set reads "... Elites that are ignited increase your damage by 2000%" This buff is shown on your bar by 50 firebird stacks. The bug with this bonus is that while fighitng a blue pack you can ignite some of the pack to get these 50 firebird stacks to last forever (unless you die, leave the game or ignite a new blue/yellow pack or Rift Guardian). To do this simply find a blue pack ignite at least one of them but make sure atleast one of them also remains not ignited. You can easily ignite one of them using disintegration wave in archon form. Stick around for about 3 seconds after igniting some of the pack then leave and the buff will stay with you until you die, leave the game or ignite another blue/yellow pack or Rift Guardian. This persists through entering new zones including greater rifts. So you can find a blue pack before entering a grift to start with 50 firebird stacks.
Gear Stat Priority notes: You do not want any extra crit hit damage, crit hit chance, or area damage on gear or paragon points. This is to control how much damage we deal with fire blast making sure we do not go over "3000%" (6.3 Billion Damage) dmg in one hit. Instead we prioritize CDR and consistent damage amplifiers such as % fire dmg, and elite dmg. Since we do not need crit or area damage we can get a lot of extra toughness on all our gear where we would normally want crit.
Now you know what the bugs are and how they work here is how all the peices of the build come together. Before entering or upon entering a grift find a blue pack to get the perma firebird stacks. Then go around in Archon which is our main ability and you will only be dealing damage while in archon form. While in archon form use ability bound to the number 1 key "fire blast" to apply the 3 second DoT. Be sure to only fire blast enemies once every 3 seconds or you will ignite them rendering them unkillable. We use the Swami and Fazulas to help increase our archon stacks which greatly increase our DoT damage so you want to stay in Archon as much as possible to overlap the archon stacks. Outside of archon we have Aether walker to spam teleport for mobility we also take calamity rune on our teleport allowing us to stun enemies by landing teleport on them. Taking calamity run on teleport also deals damage which works with obsidian ring of the zodiac to reduce the cool down on archon. We also use Arcane torrent while in a safe position to reduce Archons cool down. We also have APDs to get more damage reduction which pairs with teleport calamity rune which stuns, halo which will freeze enemies, and zeis which also has a chance to stun.
This build does work in groups with both zdps or other Wizards. If you are running with supports be sure they are not giving you chc or chd. Also be sure they don't give you too much dmg buffs putting you over the threshhold. So they should mostly be focused on increasing group survivability. You can also run multiple DPS wizards including other firebird wizards running either normal or bugged setup. Firebird wizards will not interfere with eachother. You can both deal fire dmg at the same time to mobs, your stacks do not effect each other and you can still kill mobs that have been ignited by other wizards with your 3 second dot. The only thing to be careful about running with other wizards is there is no way to tell the burning and ignited visuals apart from those of other wizards in your group, so you need to be extra careful keeping track of which monsters you have hit in the last 3 seconds.
Things to keep in mind:
1. Ignited enemies (enemies with the perma 3000% burn) do not benefit from the 4 piece bug that applies your damage amplifiers twice.
2. Igniting a new elite drops perma 50 firebird stacks and you will have to redo the trick to get them back.
3. Dying drops firebird stacks
4. Firebirds 2 peice bonus drops a meteor when taking fatal damage can ignite enemies, avoid dying on elite packs.
5. Dying on or igniting the Rift Guardian will almost always lose you the grift. If you die you can try to tp out and find a blue pack to ignite. If you ignite the Rift Guardian the ignite cannot be removed and you will not be able to kill the rift guardian and to my knowledge the ignite cannot be removed.
6. Be patient and look for high density and elites. You have to restrain yourself from spamming while in Archon. It takes a while to get used to this kind of playstyle where your main priority is positioning to stay alive and not accidentally losing firebird stacks.
1. Clarified that "3000%" dmg in one hit is inaccurate actual number hit should be something below ~6.3 Billion.
2. Changed Bane of the Trapped to Esoteric Alteration.
3. Group Game play notes.
4. Swapped Audacity to Galvanizing Ward