Here's something I've been playing at casual Dust-day at my LGS for a month or so. The core idea is that cards like... well, Cores (and Mixes) are powerful but their inclusion in the deck tends to cause you to have terminally bad draws late game. Seer should allow you to play powerful cards you don't want to draw late-game and be more likely to avoid them when the time comes. Card quality, and timeliness, over quantity. I decided to pair this with a Reanimator package because that has a similar problem: for it to be an upside, you have to draw cards in the right order and at the right time. And, lastly, it's running my pet [[Ghost Ship]] loop. Essentially, if one is in play and one is in the cemetery, they can always bring each other back (or, for maximum "fun," [[Ultimate Horror]]).

Overall, I would say it works as intended. I'm not confident yet that I'd take it to a tournament, but it's powerful, fairly resilient, and most importantly, fun to play.

Here are a few recent adaptations based on experience:

I started with [[Pith Imp]] as a speed bump for my opponent's plan. That worked well, but I'm now trying [[Fey Changeling]] because it does both that and also solves a weakness the deck has: [[Mesmerism]].
I removed [[Shrine of the Dragonlord]] and [[Onyx Core]]. Shrine not paying for itself the turn it comes down felt worse than Cores every time, and we're barely more than two colors at this point. The two Cores and 4 Mixes seems about right as the base package.
I finally cut [[Lord of the Void]] as it is powerful, but just not resilient enough.

Some cards I have my eye on:

[[Edge of the World]] might come out. The [[Ghost Ship]] plan is strong enough that my games have largely concluded in the mid-game before the void is entirely filled in. However, I haven't drawn or played on yet, so I want to see it in action before I commit. One of them would probably become [[The Void]] actually.
[[Nightmare]] may not be good enough, simply because it dies too easily.
[[Dream Quest]] may also be too cute. I'd like to draw and cast it once before making the cut, but I suspect there is no good point in the game to play it beyond a turn 3 play following a [[Sisters of Avalon]], which might be too narrow.
[[Questing Beast]] may not fit here either. Its only resilience is Stealth, so it's essentially one-shot. And it might require you to play too aggressive with sites if you Mix it out on turn 2, otherwise it just sits in your safe back-row formation doing nothing useful. A recent addition which I'm also looking to resolve once before deciding either way.
Is this the deck that actually wants [[Mother Nature]]?! That could be a powerful turn 3 play in a safe back row position off of a Mix, similar to Lilith, but better against spell-heavy decks.

Ex-Seer-iment

@Seraph