Chimaeron isn't "hard" but you will need a very good gear (I had 586) to kill him on Heroic. No Juggernaut trinket here, because it doesn't help in P2 (-99% heal taken) and P2 is where the difficulty is.
Some tricks :
Ice Block the first Double Attack
Use Temporal Shield for Massacre. Massacre does 1M, but Finkle's Mixtures prevents you from dying. However, you still take 1M, and Temporal Ripples will heal you back for 333k/ tick, which is of great help
Keep Mirror Image for P2. I also used an engineering Cardbord Assassin for an extra bit of survivability.
Armory : eu.battle.net/wow/en/character/hyjal/Araitik/advanced
Music : Olwik & Sundholm - Göteborg