I'm not aware of any minions that can't be teleported, and I'm pretty certain that bosses and above can never be teleported. I'm less certain about lieutenants - I'm pretty sure I've seen them teleported before, but I wouldn't bet a shiny penny based on my memory alone.
Just a vague guideline until someone with more solid info chips in 
@Hakeswell
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Arc: 70119 Hellion Initiation
Starless Step will certainly TP Lieutenants, but it does seem to be dependant on relative level. The chances of my successfully teleporting a foe increases dramatically as their level drops.
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I can pretty much get Minions and Lieutenants every time. Bosses are a lot harder though possible.
As for pvp, as far as I know /eng stalkers and people buffed with increse density can't be teleported. No doubt theres more.
Phaseshifting prevents TP, I've never successfully TP'd a Boss; though I can confuse Elite Bosses at times.
It says in the power description that it doesn't always work on lts, and only works on bosses much lower level than you.
Hibernate prevents friendly teleportation, so I assume it blocks hostile TP too.
I really should do something about this signature.
Thanks for the advice. Been playing with it a bit more and can teleport any mins or LTs up to orange about 75% of the time. Red LTs don't budge and red mins can be shifted around half the time. This sound about right to you?
BTW, have Trip Mine slotted 3xDAM, 2x RCHG and 1xACC - does this make them reasonably reliable and tastily damaging?
Is it time for the dance of joy yet?
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BTW, have Trip Mine slotted 3xDAM, 2x RCHG and 1xACC - does this make them reasonably reliable and tastily damaging?
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Yes they'll rarely miss. With enough you can kill anything including Tanks, Brutes and elite bosses.
We wish to bring down the whole sky,
But we never can.
What can and cannot be TP Foe'd?
Is it time for the dance of joy yet?