Some info first:
This only works with mobs that don't die, but surrenders to you at 1% hp. (Example: The quest for Sith Inquisitor where you get the Khem Val companion)
What this bug does is skip the fight and go directly to the 1% surrendering part.
It requires some luck and you might have to try multiple times to get it right.
Ok, here is how you do it:
1. Pull the mob with a ranged ability
2. Run like hell back to the phase entrance
3. Wait for the mob if it hasn't catched up to you yet (the mob must be at the entrance too)
4. Very quickly go out of the phase and back in (run out for like 0.1 second)
5. The mob is still there, but after about 2 seconds it will reset and start running back to its original position
6. Immediately cast a channeling spell on the mob (Example: Lightning Drain for Sith Inquisitors)
7. The spell should be channeling when the mob resets and starts running back
8. With some luck, the mob should instantly drop to 1% and surrender.
Found this by pure luck when I was doing the Khem Val quest on my Sith Inquisitor.
I was only level 8 and he was too strong for me so I ran out to not die.
When I entered back in 1 second later I noticed he was still there so I started channeling Lightning Drain on him and he just instantly dropped to 1% and surrendered to me.