TTK = time to kill. So let's go to DTK for the shortening of Destiny:the Taken King. And before you slap me with "haha scrub use context clues", this is meant for subject lines on forum posts. I also foresee getting hammered with "all acronyms mean something else", but TTK pertains directly to destiny pvp and is sighted and referenced a lot in that discussion. So DTK would alleviate all that.