This is only prepatch info, not a Legion info!!
Class trinket has x% chance to spawn 3 imps at your feet. Each firebolt they do has a 2% chance to spawn a Hellhound or Illidari Satyr (melee demons) at your feet.
So basically. If you stand 40 yards away from a boss, class trinket will spawn imps +- 40 yards away from boss and these imps will spawn demons also +- 40 yards away from boss. These demons then have to walk to boss before they start attacking, so therefore they are wasting a lot of time doing so.
If you stood at boss' feet entire fight, these demons would most likely have to walk 5 yards instead of 20 or 40 yards or whatever.
Anyway, this is definitely a DPS increase rather than DPS loss if you stood at boss' feet. This works only with movement unheavy fights although you can deal with movement while consuming Shadowy Inspiration stack with Demonbolt/Shadowbolt. Also, you will make it harder for your raid to have another "melee" there, and you will have to deal with both melee and ranged mechanics. Therefore, you can do it only at appropriate times :P
Thoughts?