What this guide is going to provide:
- a quick reference guide for each boss fight in Therakiel's Temple.
- information on what most players find challenging so that you can adequately prepare.
- if you have a team member who is new to a given boss fight, copy the image link for the fight and paste it into chat to give them a quick overview of key mechanics and tips on how to handle them.

What this guide is *not* going to provide:
- advice on how to speedrun the lair. This is for players who are new to the fights, not for people trying to figure out how to make it take 15 minutes instead of 30 minutes.
- build advice. The challenges are laid out in the guide. How you address them is up to you. Evaluate the problems and consider the tools available to you given your themes. Then make a few simple decisions with your team at the start and go for it.

Who this guide is for:
- players that are doing TT for the first time
- players that enjoy meeting challenges with a large variety of builds
- players that are fine with dying and enjoy the process of learning

My hope is that this will make it easier to share mechanics with team members that are new to a given boss fight by letting someone quickly copy/paste the image link for a given boss into chat instead of typing out explanations.

How will your team deal with Valerian’s mobs?
How will your team deal with Fang’s giant army of mobs at the end?
How will your team deal with the Baron’s Congos at the end?
How will your team deal with Vlad’s bats?

My team’s answer to all of the above has generally been one of the below:
Use crowd control and then kill them with moderate AoE DPS
Kill them all with overwhelming AoE DPS

Must haves:
Resurrect power or device. You’re going to die. A lot. It’s ok. Just expect it for your first run.

AoE DPS. The mobs must die one way or another eventually. Having one single target attack and using the rest of your power slots for buffs might be meta at cosmics, but that is not the case here. Have a strong AoE in your build.

Know what killed you. When (not if) you die, look in your combat tab and check for what attack or mechanic killed you. Figure out how it works or ask around so that you don’t die to it again.

Nice to haves:
Threat wipes for DPS. The bosses tend to either wipe threat or put the tank in positions where they cannot attack. The DPS need to wipe threat.

Crowd control. The mobs hurt. Having a mix of AoE knockups and strong stuns is a great way to give the DPS enough time to clear them out.

More HP and general toughness. If you go in for your first run with your most squishy character and you’re not paying attention, the mobs will tear you apart like a wet paper bag. Give yourself time to react and room to make mistakes by slotting for more CON and more defense. This applies to Tanks, DPS, and especially Healers.

Personal note:
The people who tell you that you can only do this with meta builds are flat out wrong. The lair is being done and has been done with a wide variety of builds. Melee, ranged, hybrids, petmasters (yes really), healers that do damage, DPSers that CC, tanks that heal, ATs, etc etc.

In fact it’s hard to think of passives and powersets I have not seen TT be done with.

With a little coordination with your team about how you will handle the mobs and mechanics of the fights, you can do TT in an hour with just about any powerset. Why do I say that? Because others are already doing it. If you have time and patience, there's no reason why you can't do it as well.

This is a first pass, and my knowledge of this lair is limited, so I'm expecting a better version will come out soon, but in the interim here it is. This only covers the boss fights.
General
All bosses in Therakiel’s Temple are hard hitting; all of them also spawn large numbers of dangerous (master villain or enforcer) adds. Unlike Telios Ascendant, where the adds have a fairly low spawn cap but respawn rapidly, making them convenient to babysit with an offtank, the adds in Therakiel’s Temple you generally want to kill. The recommended roles are:

• Add tank (tank capable of generating area threat and generally rounding up adds).
  
• Main Tank (tank capable of holding boss aggro). It’s possible to have one tank fill both roles, freeing another dps slot, which is useful but also harder for the tank.
  
• Healer. Surviving is challenging because of the adds mentioned above, you’ll need to invest significantly in survivability.
  
• Area dps (everyone else). You don’t really need super high single target damage (it’s nice to have, but not essential), but there’s a lot of adds that need management. Spike damage ultimates, because they have high target caps and don’t draw aggro until they’ve already hit (hopefully killing whatever they hit) are particularly useful. All dps should take threat wipes, the various boss mechanics make it difficult for tanks to hold threat.

Valerian Scarlet
The general flow of this fight is

• Eldritch Blast: Val’s basic charged attack (*bam* tell). Fairly high damage in a moderate radius around the main target, knockback if not blocked. Used through the fight.
  
• Soul Sigils: At the start of the fight, and at intervals through the fight, Val summons five yellow glowing sigils. These do magic damage to people near them, and after some period (I think 30s) they explode, which will wipe the teams, so they should be killed quickly by the dps. They have around 15k hp each and negligible damage resistance, but can appear anywhere in the combat area, so keep an eye out for sigils lurking in back corners.
  
• Skarn’s Bane: used occasionally through the fight. Cone area, no shtick tell. Damage not particularly high, but strips form stacks, and eventually also strips defiance stacks.
  
• Gleaming Fire: used occasionally through the fight. Targets a random player. Visible tell is a fiery sphere around the target; after a few seconds it collapses, causing fire damage and paralysis in an area. If you are targeted, block and move away from other players.
  
• Teleport: at 2/3, Val teleports to the floor (if she is not already there). At 1/3, she teleports to the ledge (if not already there). At about 1/10 she teleports to the floor.
  
• Seething Soulstrike: After her first two teleports, Val puts down a magic circle, summons soulbound slaves, and uses a maintained beam. Applies a stacking debuff to the target. Beam ends when the soulbound slaves are killed, so when this happens the dps should prioritize clearing the adds.
  
• Expulse: before her second and third teleports, Val uses expulse (large area, moderate damage and knock).
  
• Blinding Light: after her third teleport, Val puts golden star symbols under each character, which indicate a golden light beam (similar to Vengeance) arriving in a couple seconds, doing enough damage to instantly kill. Wait for it to form, then step out of it. She will continually do this until dead.

Black Fang
This fight has a bunch of adds that are pretty dangerous and like to spam knocks and holds. Black Fang's key mechanics are:

• Block Hatred: every time certain of Black Fang's attacks are blocked, he gains a stack of a buff and refreshes his original stacks (duration 15s). If that buff every reaches 9 stacks, he starts doing huge damage and breaks blocks, rapidly wiping the party. The main tank should try to keep him at 0 stacks most of the time, as he's likely to acquire stacks when he target switches.
  
• Black Iron Cyclone]: Black Fang spins a chain; all targets are pulled towards him, targets within 50’ also take damage. The damage starts fairly low and increases every tic. He only builds block hatred if the main tank blocks the first hit.
  
• Claws: Black Fang mostly beats on the main tank with a three-hit claw combo. The third hit is an area effect. Reportedly the third hit can be blocked without generating hate.
  
• Horn Gore: every so often, Black Fang will root someone and then charge at them. Blocking this does build up his hate stacks, but for the most part it should be blocked anyway. He also announces “Cull the Weak” in local chat.
  
• Bad Dog Stomp: at 2/3 and 1/3 health, Black Fang will become unattackable, leap up, drop back down (applying strong area damage and a knock-to), roar (applying an area hold), and wipe threat on the main tank, switching to a secondary target. Everyone should block when he leaps, and DPS should be prepared to threat wipe (to avoid giving him too much block hate)
  
• Summon Army: at about 1/6 health, Black Fang starts summoning large numbers of berserkers, which will roar (buffing everyone’s damage, including Black Fang, possibly applying holds or knocks). You can either kill them (high damage area ultimates are nice here) or have an off tank pull them while the dps finish off Black Fang, but they do a lot of damage so killing tends to be preferable.

Baron Cimitiere
Key mechanics are:

• No Resurrection: res powers (either self-res or res others) do not work in this fight.
  
• Block at the Start: Baron Cimitiere tends to target a random character at the start, which is plenty to kill a non-tank. Starting the fight down one dps or healer is not good, so block while first engaging.
  
• Curse: Baron Cimitiere waves his hands and puts a curse on a random target. This causes them to be disabled (cannot use powers and removes travel powers, but can move) and puts a green starburst type animation under the character. When the effect ends, causes moderate damage (~3.5k) to character, high damage (~20k) around the character, so a cursed character should move away from others.
  
• Curse Pit: Baron Cimitiere waves his hands and puts a green pit animation under a random character (might be a different animation from the above, but if so I can't recognize the difference). This create a lasting damaging zone which you should move out of. When he starts doing his curse animation, you should move to a location where you don't mind a fire pit.
  
• Near/Far Block: Baron Cimitiere will tell you to stay away or come close, and start blocking, creating a green foggy zone around himself. Do the opposite of what he tells you to do (or take large amounts of continuing unblockable damage) and stop attacking him (he still has his original reflective block). I don't know if Break Through will break his block, someone should test that.
  
• Serviteurs: Serviteur zombies get continually summoned through the fight (a parse I have shows 80 of them being killed in a single fight). They do substantial damage and have collision (which is a problem during his near/far phase) so they should baited by an add tank and thinned out by dps.

Vladic Dracul
Key Mechanics are:

• Bats: large numbers of bats get summoned (directly on top of characters) through the fight. Bats do moderate damage (squishy characters should be prepared to use active defenses if alone), remove travel powers, and apply a stacking perception debuff. They are resistant to single target damage and vulnerable to area damage and heal as they attack. DPS and OT should be set up to kill them. PBAoEs are good as they are unaffected by perception debuffs.
  
• Blood: the blood pool below Vlad will cause him to heal if you stay in it too long. Generally safe to run through while killing cages, but don't hang out there.
  
• Cage: Vladic says 'away with you' and banishes someone to a cage somewhere in the room. The cage (which appears as a red glowing thing under the cage itself) must be destroyed. Avoid getting too close, the cage object holds a nearby character which is supposed to be the character in the cage, but it's possible to have it hit someone else. This can hold the tank, which will cause him to change targets. Dealing with cages is generally the job of dps.
  
• Dark Bolt: this is his ranged spammable attack; it appears to be a three-hit combo doing up to 19k. Non-tanks should block.
  
• Eternal Maw/Condemn: Vladic uses Eternal Maw (Bite animation) at short range or Condemn at range. Either one will heal him by a lot of not blocked. Condemn is area effect and will heal him for each target hit (do not use pets). Everyone should be prepared to block, there are several ways the main tank can lose line of sight, resulting in him switching targets. DPS should threat wipe frequently.
  
• Runeblade Strike/Annihilation: mostly he hits the main tank with a medium damage (and 180 arc) combo, occasionally mixing it up with a quite high damage charged strike. Other than not facing him towards the dps, nothing notable about this.
  
• Shadow Eruption: PBAoE attack, moderate damage, knock, travel power removal. A poorly positioned tank may get dumped into the blood (standing with your back to a pillar helps), and without travel powers it takes a while to get back up, during which time you lose line of sight and Vlad switches targets.

Therakiel
Therakiel’s basic attacks follow the normal standards for tanking -- don’t point him at the dps, don’t stand too near others -- and are otherwise unremarkable. After the first third of the fight, the setting moves from the temple to standing on air, which can make it hard to judge distances accurately. Specific mechanics to note:

• Anaktals: during his first third, Therakiel will summon ten Anaktals. Unlike most adds in this lair, these have a spawn cap and get respawned if killed (and are deleted once he drops below 2/3) so it’s useful to just tank them.
  
• Burning Aura of Glory: first at 2/3 health, and then at intervals, Therakiel goes into a block stance and glows with blue flames. He acquires two buff icons -- one for Burning Aura of Glory, one for either Dark Empowered or Light Empowered. During this period he is immune to damage and reflects attacks, and over a couple seconds he summons three Hellementals: one colorless, one Dark, one Light. Hellementals, when killed, create statues of an appropriate color (random for the colorless), and you will need an aura of a color opposite to his empowered effect, or you’ll die. Hellementals explode if not killed fast enough, and this phase ends when all Hellementals are dead. Make sure to get the color you want in the first two, you don’t have enough time to pick up an aura if you kill the right color last.
  
• Cloying Nightmares: Therakiel summons purple pillars that will move slowly around following nearby characters, doing irresistible damage (looks like about 10% of hp per hit, on a 0.5s tic) and snaring victims. The tank should pull Therakiel away from them.
  
• Dark/Light Empowered: After his Burning Aura of Glory phase, Therakiel emits an aura that tries to kill anyone who lacks the appropriate defensive aura. Damage is 50% of health on the first tic, 100% of health on the second tic, irresistible. Be careful about positioning, if you walk into a statue of the wrong color’s aura you’ll die before you can do anything to fix your mistake.
  
• Fire Beams: Therakiel uses eye beams on a target, who is held and takes increasing fire damage over 10s (starts at about 900, ends at about 3500) and then gets killed (200% of health irresistible). To free a victim, stand in a light beam and aim your mirror at the victim (this also takes Therakiel to take trivial amounts of damage).
  
• Shadow Lunge: Therakiel roots a random target, then lunges at them. Does about 6k (base) if blocked; if unblocked does an extra 34k. Also causes knockback.
  
• Therakiel’s Bleak Glory: Therakiel spins his sword like a giant propeller, at the end of which he causes damage and knockback. If he is dark empowered, block. If he is light empowered, do not. Getting it wrong kills you.