Tichondrius is fight that will require quite some healing from you due to the constant damage from Carrion that will ramp up throughout the P1 as more and more people will be affected by it, meaning that Seeker will also hit more people dealing overall more damage to your raid.
Considering the point above and the fact that tanks will also get hit hard by the boss or the adds mean talenting into cycles is a good idea as you will be able to cycle easily during the fight. You may argue that since you can regen a lot of mana thanks to cycles but the P1 last for about 2min, you can easily oom yourself before the P2 starts.
In addition to this damage the boss will cast Brand in Heroic and Mythic difficulty, if your strategy implies to make them explode, make sure to time your Revival on one explosion, they come as a pair so using it on the first explosion allows your raid to pop the second rapidly after the first. The rest of the time make sure to time your Chi Burst correctly when one brand explode.
Your Chi-Ji should be used as soon and as much as you can, wait for the first Brand that pops to use it, you can also time your Perfectly Preserved Cake on the brands (make sure to have 6 people in range, you can blow it in melee if necessary to get the 6).
In the third P1 there will be a demon add that will pop, he doesnt do much except casting DebuffH on a healer, be ready to dispel it quickly so it doesn’t dry all of the poor targeted healer’s mana.
On this fight Diffuse will offer you a nice damage reduction for either the explosion of brand or for a Seeker and those events are the most common deaths here. But if you feel really safe and find yourself struggling when the Plague is on yourself then you can talent into Elixir to help you a bit with the ticking damage while stil providing some utility for the major events.
We cannot be targeted with Brand but we will still count towards its explosion like any other player so even though you can’t be target it’s not recommended for you to stay grouped with others ranged to avoid any uncontrolled explosions.
And just like any other player you can also be targeted by Plague so make sure to place yourself accordingly if you are affected by it.
You can use your Transcendence to easily hide behind a pillar during Pillar by setting your spirit in a corner away from the boss, you will be able to instantly go behind the ranged pillar of your choice. Don’t forget to set it again as there is two pillar phase per P1.
If you can afford (ie. not too much healing required) you can spam SCK during the P2 to help kill the bats, you’ll actually deal more damage to them than some dps specs !
In mythic the Brand will let a pool of flame burning for 1min, meaning that if your raid decide to pop them, your raid will be split in two and you won’t have range on your EF to heal the other group of ranged unless you move towards them, thus taking more damage from their brand and putting you in danger for the brand of your group, I recommend you only do that if you’re certain you’ll be out of danger for the second brand explosion. You can afford staying in the fire pool with Diffuse.
In Mythic mana is required to survive the return into P1 after the end of the P2 so be sure to get yourself a debuff ! But do not be greedy as the first debuffs shall go to the dps that can easily burst down the bats to secure enough debuff for all your raid else you might not get 20 bats killed and thus having people dying.
Another difference is that Swarm will now deal 400% increased damage to people affected with Plague but will stop at the first target hits, meaning you’ll have a single person soaking every Swarm depending on your comp you may not have to heal the stacked Plague bearer but if you have to make sure to keep on eye on him with EnvM as necessary.