Because I'm really, really tired of watching healers faceplant into the floor for stupid reasons. I'll admit that solo healing CT is a lot more entertaining than using Medica II and afking for 30 seconds, but come on, a lot of this stuff is basic and not difficult.
Valefor's Tail Swipe can be Esuna/Leeched.
Should the tanks be positioning them properly? Yes, but in the event that you have a troll or one of the tanks is just outright bad, immediately Esuna as many people as you can save, top yourself off quickly, and then heal everyone else back up. You have no excuse to be dying to the DoT, and stop trying to power heal through it.
Bone Dragon applies Disease shortly after pull and it can be Esuna/Leeched.
It's amazing and sad how many people leave disease up on the MT. You can power heal through it but why bother? Stop being lazy.
Stop spamming Medica II.
This is for the WHMs. You only need to Medica II once and then Medica once more if needed (it usually isn't). In particular, do not Medica II right before the eyes on bone dragon or the iron giant on Acheron spawn.
One healer can DPS on Atomos.
You really don't need two healers for this. One dedicated healer or two half-heal, half-DPS healers is more than enough. Alternate Regen/Adloquium/Stoneskin and you're good to go.
Magic Pot at Thanatos can be full healed with just two Lustrates.
This is for the SCHs. If, for whatever reason, you neglect to heal your pot normally, then you can double Lustrate it to break the tether. If you have a SCH in your party and your pot gets chained all the way to Thanatos, that SCH is bad and should feel bad.
Behemoth (A): Don't stand near the comets when the Iron Giant is up.
The comets will periodically explode and burn anyone nearby. Don't take unnecessary damage, please.
Behemoth (B): Comet Burn can be Esuna/Leeched.
Same deal as with Valefor's Tail Swipe. You have no excuse to be dying to the DoT, which shouldn't be on you to begin with.
Virus Acheron at the start of each phase.
His first few attacks seem to chunk hard. Be prepared for that damage, especially if the tank isn't well geared. After those few hits, the rest of Acheron's attacks are weak and he spends half the time channeling anyways.
(WHM Holy and then) step off the platform after Ancient Flare goes off.
You can stun the giant, and then run out of the way in case your tanks don't turn the Iron Giant to avoid the cleave.
Acheron always uses Quake after Megiddo Flame and Quake III after Moonfall Slash.
Pre-cast your Medica/Medica II/Succors please. People shouldn't be dying to the hands because they got grabbed at 500 hp because you took 5 seconds to react.
Valefor's Confusion and Comet Burn are the two that annoy me the most. So many healers just sit there trying to heal through it and let everyone else die when all it takes is a few Esuna/Leeches to save everyone.
To add to this, you can focus target Acheron as well to see which attack is coming up - it's useful even outside of CT (e.g. Hydra). You can also FT your MT or OT if your party isn't doing anything big (e.g. Bone Dragon, Behemoth if both your tanks are on towers).