Senior Loyalist Tilas is the first named encounter you will find in TotMC. This mob is largely tank and spank. He comes with 2 Epicx4 adds which can hit pretty hard but are largely beefed up Heroic adds.
Tilas has been known to do a large AOE at times that is currently undetermined what causes it. He will say something to the effect of "See how I will turn the winds of these caverns against you", and you will see all his detrimentals fall off of him and then shortly afterwards a massive AOE will hit the raid.
One common thought is that the mob requires a certain level of DPS being done at any given time and if the dps drops too low when he shakes his debuffs he will AOE. It has only been seen a few times in doing the zone.
Kill the adds, burn the named. Congratulations on your first TSO pattern drop (cuffs).