As far as consistency, I'm not really sure what to say. Standard is not overly friendly to tri-colored decks at the moment. Especially ones that don't run green. They can work, but they feel a bit more clunky than they did before this most recent rotation. A couple
Evolving Wilds or Warping Wilds may help a little though. They allow you search for basic lands to fix what mana you have available. Plus a shuffle may save you from getting mana screwed. I know they were in an earlier iteration of a deck you had posted, but I can't think of anything in the sets you're asking for that will really help.
As for dealing with that combo... It's going to be a pain because it's a tough one no matter what. Now, despite your requested parameters about set, I'm going to say
Hallowed Moonlight. That will end that combo.. But, since Origins is apparently a no no, I would suggest added removal that lets you target the victim of your choice. You could probably drop the artifacts in your sideboard for another
Lightning Axe or two, as instants work best against these annoying
flicker strategies. Another option is to add
Murderous Compulsion, since you run Madness, as creatures flickered by the Displacer return tapped and playing the spell through Madness can work at instant-speed. More Anguished Unmakings would work as well. I just feel part of your problem here is that the bulk of your removal hinges on Sorceries and Creature abilities. Both of which are going to see the Displacer dancing all around you and controlling the game.