For 15 seconds after the Temporal Smash is used, Chronomatic Anomaly takes 30% increased damage. Players should save their DPS cooldowns for these moments.
Being this is quite an important piece if information for dps, it's a natural for making a Weakaura but, can't find the debuff name anywhere. I'm guessing the name is actually "Temporal Smash" though wowhead is inconclusive.
A guildy claimed he saw a debuff on the boss for it so I assume a specific debuff exists. I guess I could trudge through LFR and look for it in the combat log or pile of debuffs somewhere but I thought I'd ask here because I assume others may want to know this as well.
Last resort/workaround would be making a slightly more complicated WA that goes into Event - Combat Log and counts 15 seconds after Temporal Smash is cast.