Tier 4 Dungeon changes
Polaris
Haugbui Jarl
New ability: Electrified Strike. Cannot be interrupted, massive tank damage that needs a cooldown to mitigate it.
Blarblane Sorceress
New ability - Maddening Melody. Places red circles and Maddening Melody dot on random players. Any other players standing in the red circles will also take damage.
Deathsquall damage increases the longer you stand in the AoE, (so don't tank in it).
The Varangian
The adds are more of a pain to kill - don't run into the second area before killing both packs of adds in the first area.
The electrified crates do more damage the longer you stand on them. Your healer may be able to cope, but you may also need to move around.
Haugbui Mother
New Mechanic: Maddening Melody. She applies Maddening Melody, same as the Blarblane Sorceress. Don't overlap the circles and just heal through it.
Primordial Dweller
Adds are harder to control as we don't have the Crystallised Blaze slow any more, and grenades do less damage. When adds come, make sure to move to the tank in the middle to help pick them all up. Bomb adds now require extra attention to burn down fast.
Ur Draug
Changed Mechanic - Strength from Beyond. Blue phase gets a bit hardcore. The damage reflect during blue phase does a lot more damage (the first second or two are ok, then it ramps up). DPSing through blue phase doesn't work any more, even with Unveil Essence, you'll just die.
UD doesn't use Pulverise as often, so pillars are more likely to last through blue phases.
New Mechanic: Maddening Melody. In blue phase, UD will cast Maddening Melody on several group members. This does about 1.4k per tick, so if you stack up the red circles will massively increase your damage taken. Try to spread out behind the pillar, keeping out of sight but not overlapping circles. It's very easy to lose track of Ur Draug at this point and get hit by Cosmic Sundering, so be careful!
Darkness War
Killing adds deals damage to the whole group. Do not kill large numbers at the same time, take it steady, or the healer won't be able to keep up.
The Darkhouse Sorcerer and Mayan Battle Mage now have multiple stacks of Itzama's Wrath that need purging.
Unbound Ak'ab
Changed mechanic - Dash. Changes to his dash means that it'll still hurt even if you've got him faced against a wall or rock. Basically, don't stand in the column to avoid the damage.
Because the fight is longer, be prepared to handle several burrow phases and waves of adds.
Hell Raised
New mechanic: Soulburn. Any time that you gain any stacks of Lifeburn, you will also gain the debuff Soulburn. Soulburn does no damage, but it prevents you from being cleansed. Soulburn has a duration of 6 seconds, so you'll need to heal through 6 seconds of Lifeburn before you can cleanse any stacks of it.
Antimony Ministrix
Changed mechanic - Macroshock. Can no longer be interrupted. It will chain through the group, but deals less damage now. Basically you just have to drag her around the pillar, keep out of the purple circles and heal through the damage.
Corroder
New mechanic - Caustic Puddle. The Corroder will drop an AoE under itself at the end of the Caustic Outpouring channel. This puddle lasts 20 seconds, which is about enough time to drag him to the other end of the path and go through another Caustic Outpouring, so the tank needs to move him up and down the path. The boss still cleaves, so you need to be a little careful moving back through the group. The tank can move behind the Corroder during Caustic Outpouring to be ready to dodge away at the end of the channel.
New mechanic - Flame Armour. The Corroder will apply 5 stacks of Flame Armour to himself. This will deal damage to attacking players when they hit him, and should be purged ASAP.
Hardwired Fleshtank
New mechanic - the lava around the platforms applies Lifeburn. Standing in the lava around the platforms applies stacks of Lifeburn (and Soulburn). The longer you stand in the lava, the more stacks you'll get. So basically, jump between the platforms, don't just run through the lava.
Traumadriver
Changed Mechanic - Molten Metal. Molten Metal will still deal damage within its radius, (which now has a chalkline to help you avoid it,) but will now apply Lifeburn to the whole party, even those over 10m away.
New(ish) Mechanic - Hellsword. This is the same mechanic used in Dark Agartha. It creates a sword shape of small AoEs on the ground, that then swings. The Traumadriver will be looking in the direction that the sword will move towards, but if the tank isn't facing him towards the wall, it can very easily wipe the DPS.
Recursia
Changed Mechanic - basic attack. Recursia no longer cleaves, and no longer hits as hard with her basic attack, (it won't one shot DPS any more). The attack will now chain to all members of the party, with an 80m range, so you can't outrange it even if you scatter to the edges of the room.
Changed Mechanic - Infernal Criticality. Now applies 3 stacks of Lifeburn at the end of the cast. You'll get Soulburn too, so it can get a bit spicy for the healer as you have to heal the group through 6 seconds of 3 stacks of Lifeburn before you can cleanse, and most abilities also only cleanse 2 stacks now.
New Mechanic - Sole Purpose. The Rakshasa adds will now instantly die if rooted, knocked down or stunned.
The Rakshasa adds move surprisingly fast, which can make it hard to DPS them fast enough. Using extra abilities to insta-kill them will help. It's really important not to stand near the boss during the add phase now. Lower DPS means the chances of accidentally dropping an Anima Eruption shield in a bad place is much higher. Try to stay as far away from the boss as you can during the add phase, and remember to look behind you for adds waiting to be summoned. If you can avoid standing in front of new adds, that helps reduce the chance of inconvenient shields.
Machine Tyrant
Changed Mechanic - Lifeburn. MT's Lifeburn is also applied in stacks of 3. It's helpful to have 2 people cleansing, as the healer may be pushed hard by keeping everyone up during Soulburn.
Ankh
Squalid Hekaturgist
New Mechanic - Rebirth. The Hekaturgist will periodically cast Power of the Ankh, giving himself 5 stacks of Rebirth. If he reaches 0 hp with stacks of rebirth, he will be healed for like 10% per stack. It's purgeable, so best purge as soon as you see it!
New Mechanic - The Reborn. The Hekaturgist will call up mummy adds called The Reborn. They each pick a target and will have a little red line linking them to their target to show who they're hitting. They can't be tanked or taunted, and have way too much hp to bother trying to kill them. They don't do massive damage, (about 1k per hit,) and can just be healed through.
Dr Klein
Dr Klein on the bridge hasn't changed, it's a pain enough already! Just remember to have a tanking cooldown ready for Dreaming Shroud, and be prepared to heal hard through it.
Orochi Dead Ops
New Mechanic - Rebirth. They all cast rebirth, so focusing them down one at a time is even more important. This helps you to burn through the stacks of rebirth together, instead of splitting your fire and ending up with them healing. This is also a handy fight to be using the new faction marking items.
Dimensional Arachnid
New Mechanic - Broodlings. The boss will summon little spiders to come bite you. Like the Reborn from the first boss, they can't be burned down, you just have to heal through the damage.
The Research Assistants all take longer to die now, so it's worth working together and not splitting the DPS too much. Be prepared for the boss to summon more of them than you're used to, as the fight lasts longer!
The Colossus, Melothat** (on his bridge):
This fight hasn't really changed much in terms of mechanics. The only real thing is that the Gates can now be hit by AoE, so grenades and crystallised stuff will now hit them.
The noticeable difference is that this is much more of a DPS check now. The boss takes a LOT of damage to kill, and his summoned adds are a bit harder to control now that we've lost Crystallised Blaze's slow, and incendiary grenades are weaker. It should hopefully be better on Live as we'll have a damage boost from agents, but I've not yet managed a kill that didn't involve winging the boss at the end. Another handy trick is to wing the gates, as it'll give the DPS more uptime on the boss, but this one's REALLY tight.
Melothat and Klein
New Mechanic - Akhenaten's Legacy. Melothat will summon adds called Akhenaten's Attendants, which act like the Reborn and Broodlings from earlier bosses. What makes this more interesting is that the number of adds he summons is based on how many stacks of Primordial Call he has. He automatically gains stacks every 42 seconds, and at 10 stacks you will get about 4 adds each. Your healer can't keep up with that kind of damage for long, so if it gets that high, you're a bit stuffed. Luckily, the Primordial Call stacks can be purged! So help a healer out, and bring your purgey goodness.
Hell Eternal
Lustrehunter
Changed Mechanic - Occluding Lens. Occluding Lens now acts like a full on damage reflect shield, so it'll mess you up if you shoot it! Not sure if Unveil Essence is enough to mitigate the damage of it yet, but it's easier if you just slow down or take a break from pewpew till the shield's gone, (it's only a 10 second duration atm).
Prime Maker
First off, it's worth noting that Prime Maker has gotten a speed boost. Kiting him isn't really possible now, as he'll catch up.
New Mechanic - Soulburn. Just like in HR, any time you get stacks of Lifeburn, you'll also get Soulburn now, which prevents you from being cleansed for 6 seconds.
Flagellatrix Superior
New ability - The Masochist. Not content with summoing little hell soldier's the Flagellatrix now also summons a big guy to help kill you. This is a bigger guy that is summoned when Flagellatrix activates Vigil. So instead of just running away during the alarm, you now have to run away AND kill the add, whilst staying ahead of the Piston Predator patrols. It's not too complicated to do, just be aware that the tank will need to grab the add instead of leading the group in running away.
Eblis
Changed Mechanic - Drink Deep. This can no longer be interrupted, and will heal Eblis for a big chunk of the damage it deals.
Changed Mechanic - Occluding Lens. Once again, this is now a proper damage reflect shield, and should be treated carefully to avoid oneshotting yourself!