"The Broken Wolf, the one whom Death has known, shall fall and be consumed by the Midnight Towers."
What if the Broken Wolf is really Slayer?
We know that when a wolf is taken by a Darkhound, the wolf's soul becomes twisted and it becomes a Darkhound. So what happens when a Wolfbrother is taken by a Darkhound? Logically, it should produce a dark version of a Wolfbrother. We know that Slayer shares a lot of the Talents in Tel'aran'rhiod with Perrin and definitely has some sort of direct antagonistic relationship to the wolves. If Isam/Luc is a fallen Wolfbrother, then that would absolutely make him a "broken wolf."
We also know that Moridin is the only Forsaken who has a sustained relationship with Slayer. Moridin's name means Death, so Slayer is also a perfect candidate for the "one whom Death has known."
The problem with this theory is the next sentence in the prophecy: "And his destruction shall bring fear and sorrow to the hearts of men, and shall shake their very will itself."
If Slayer is the Broken Wolf, and his falling will bring sorrow to the hearts of men, it must be the case that Slayer will somehow be redeemed and end up on the side of the Light (just in time to die). What if Perrin somehow saves Slayer's soul. Luc and Isam were not evil before they disappeared, so something happened to them to make evil and force their souls into one body.
As a final note the previous Dark Prophecy that we have in its entirety, the Blood calls Blood prophecy in The Great Hunt, mentions Slayer. Clearly, Slayer is an important figure in Dark Prophecy.