Frozen Retreat is a skill that the Warden can use to pull an enemy to them and snare them, or an ally to you and give them haste. It can 100% be reflected by DK's, and most of the time it gets me killed by putting me out of position of my team in a battleground.
With that said .. this is just wrong lol. A DK purposely reflected my Frozen Retreat I had placed down on top of someone's spawn in a BG (completely legal, people sit there on top of their spawn and I can pull them off the safety of their perch) and it actually pulled me into their spawn, upon which I instantly died by environmental damage. See the death recap where Frozen Retreat did damage to me, and see the Environmental Damage.
PC-NA