Eldrazi Displacer has had a dramatic impact on Standard and has demonstrated a surprising amount of playability in Modern, so I supposed it was only a matter of time before the card showed up in Legacy. And by "showed up", I mean was featured as a four-of in the deck that Adrian Throop won last weekend's Legacy Classic with in Atlanta.
Where Oath of the Gatewatch led to a pretty large overhaul of the Modern archetype, the changes to the Legacy deck add up to fewer than ten cards of difference. The full set of Displacers are the most dramatic change, and some copies of Mishra's Factory have shown up help with the colorless requirement.
Most of the creatures featured in the deck aren't incredible to displace, with Stoneforge Mystic basically being the highlight and things like resetting Phyrexian Revoker and blinking a Flickerwisp to blink a non-creature permanent also being useful. Where the value really comes from is in the reintroduction of Mangara of Corondor to the deck.
Mangara was a fixture of this deck for a long time, with the primary combination being to activate your Mangara and then to Karakas it back to your hand with the ability on the stack to exile your opponent's thing and recur your Mangara. Displacer adds more cards that combine in this manner to the deck, and only requires three mana where Karakas technically required four.
Thirteen white sources is pretty light, and it's probably ambitious for me to want to see Eldrazi Temple and Thought-Knot Seer show up in this deck, but a man can dream. Wining one tournament doesn't necessarily mean that this is a straight improvement to the archetype, but I believe that this build is definitely worth exploring. Displacer may look like a clunky card at first blush, but it has continuously surprised me and others in both Standard and Modern.
If Mangara ticks up in popularity then it might be a bit under-priced in the $3-4 range, though the real buy from this list is foil Displacers. I see no reason for the card to stop being played in Modern in both Eldrazi and Taxes and Bant Eldrazi, and it's entirely possible that this Legacy deck is the real deal.