Having tanked this a paladin, which i assuming from the log (That or your a druid tank)
chimeron is one of those fights that favours some sort of block mechanic as the critical block from a warrior is strong but cant be relied upon, where as a paladin blocks 40% Damage most of the time (Im currently running 85% total avoidance)
This is what i do when i take a double attack
100% Health : WoG Myself for about a 20-25k Bubble, Yes WoG is op..
90% Health : Use divine protection this is ussualy enough to survive it if you are running with 180k HP + with raid buffs
60-70% Health : Use a major Cooldown , Guardian of the ancient kings
Anything below 60% : At this point i know im going to die however due to how finkles mixture works you dont actully die from the first attack thus Ardent defender/ guardian spirit will save you since you didn't technically die from the first attack.
Few tips for the fight in general
IMO Paladin tanks with a WoG spec are very well chosen for this fight as they are able to help your healers by healing someone every 9 seconds this is enough to save someones life. also holy radiance can help with the raid healing during fued however its extremely mana intensive on a prot paladin costing over 6000 mana from a 24k mana pool, you will not be able to maintain your threat rotation, but you will still be able to use crusader strike and judgement on cooldown thus allowing you to use WoG
Have your paladins LoH the main and the off tank just before mortality. thus giving your dps maximum time to kill the boss
Chain guardian spirit if you have 2 holy priests
if DPS during mortality is a problem have a DK DPS MT the boss since he cant technically die from 1 hit its valid for a dps to tank the boss as long as hes over 10k health
During mortality make sure your rogues are next on the threat list after the tanks as they can tank the boss for quite a while due to there high dodge rate and Evasion, the boss has a 4.6-5.0??? swing time (Dont quote me on that)
PS : This one of those fights where people think gemming dodge is right, dodge cant be relied upon and some unlucky melee hits you will die, our druid tank was gemmed full agility and couldn't survive a double attack if he didnt dodge one, make sure your tanks maximise stamina as this will also help for cho'gall which alot of magical tank damage is present
edit: If you have any unholy dk's in the raid make sure there not killing there selfs with unholy frenzy after dropping to 1 hp, took a few attempts for our dk to figure this out and he died to it about 6 times when we progressed on it