Pray. This dungeon sucked in season two, it still sucks now. The balancing Dev needs God because the changes did nothing to address the issues of the dungeon (the trash). Joking/memes aside…
Start of the dungeon
With the assumption you are doing the standard first pull of a 206696 pack into 212826, you will potentially have an overlap of the two AoE casts (427609 from the 206696 and 448492 from 212826). Depending on the key level, you might need to utilize LoS for one or both of them.
Special Tech note: If you are channeling ec, you do not take damage from 448492. As well as any persistent effects which make you immune to slows (such as 1044). You can also avoid this with deepbreath while flying. If you get 453461'd due to being stacked and unable to see it, you can caut it, rescue out of it, or deepbreath.
stasis the caut as one of your three spells on the opener so you can negate the two first 427621 from the 206696. Prioritize kicking something to help since these are all kick heavy packs. Better casts are 427469 and 427356. 427357 is more ignorable.
Since people are collectively deciding to go right, we have a new miniboss to cover. 212831 does AoE damage that leaves a DoT with 427894. You can set up “budget mass dispel” by deadcasting stasis with nat. Be very careful with potential overlaps of DotS with 206699's (there's an awkward server delay b/t the flag of the bleed falling off when someone is fully healed).
Pulling this miniboss causes the miniboss from last season to switch places with 239834. You will have 239834 on boss and the priest (239833) on trash now.
207946
One major change is that the 1238780 does AoE damage and targets at a random player. It also leaves behind ground effect. Boss fight is really easy now compared to last season since you only need to have your tank kick boss and then everyone else rotates kicks on 239834. The other minor change is the boss leap, 447439, was changed to last longer but do less damage. This will mean you can't ignore the leapt person anymore because the shield was immediately bursted. Use Externals on this player and rescue them if need be out of the ground effect.
Entering the Church
No joke, probably the hardest and most annoying trash to deal with this entire season for healing. Your timings need to be perfect or really good to deal with successive 448791 casts from the 206704. Very strongly recommend having an addon or Weak Aura to tell you when one is casting it. As Preservation, you can pair each 448791 cast with a pre-cast or healing cooldown. loomithars is exceptional here. Your first pull will have four 206704 if doing the lust pull and then you have two sets of two. Healing two 448791 should be more or less easy. It's when they're chained together and you start having to deal with an 8th cast.
Example: Start Channeling fb into first 448791, use sb the same way, echo and then lb chronof for 3rd, zephyr and externals 4th, rewind 5th, lb ec 6th, and so on until they're dead.
207939
Pretty simple and straightforward. Unchanged from season two. Just use a defensive if you want to soak and use zephyr if your group wishes to grab them all at once (does AoE when picked up by someone).
Trash inside the Church
Good cast for you to handle is the 444743 from the 221760 because it happens very infrequently. Use Externals for whomever gets targeted by the 448787 from the 206710.
For 217658, he pulses AoE damage constantly from 451763. Just focus on putting out max healing. Spread db and rev to your party with full powered echoes (not ta) in order to help. Otherwise, just take it slow and don't overly panic. Space out your healing CDs and you'll be fine.
207940
Unchanged from season two, just make sure you turn around for 428169. In phase two, this will start doing more damage (she buffs herself with 429091), so you will need to defensive each at that point. You can lslide a side in the intermission and then wbuffet and alternate ass for the other side to control the mobs.
If needed, in phase two, you can LoS behind a brazier to avoid her 428169 damage. If you get targeted with 451605 right before, use a strong defensive.