Complex sentence: His appearances nearly always involved some form of time travel, based around his particular specialty referred to as "time travel hypnosis", a process that simulated time travel; the stories themselves are less than clear on this respect.
Split into simpler sentences: His appearances nearly always involved some form of time travel, based around his particular specialty referred to as "time travel hypnosis", a process that simulated time travel. The stories themselves are less than clear on this respect.