I've been talking about this deck on Twitter for a week or so and figured I'd see what thoughts people had over here.(*)

The basic idea was to take the Sylvan Mentor chassis but swap the red for black. Here's the current list I'm on:

Main Deck
Creatures

• 4 Monastery Mentor
• 3 Deathrite Shaman
• 1 Snapcaster Mage

Planeswalkers

• 1 Jace, the Mind Sculptor

Enchantments

• 2 Sylvan Library

Instants

• 1 Ancestral Recall
• 1 Brainstorm
• 1 Dig Through Time
• 1 Disenchant
• 1 Flusterstorm
• 4 Force of Will
• 2 Gush
• 3 Mental Misstep
• 1 Murderous Cut
• 2 Swords to Plowshares

Sorceries

• 3 Cabal Therapy
• 1 Demonic Tutor
• 1 Ponder
• 1 Preordain
• 1 Time Walk

Artifacts

• 1 Black Lotus
• 1 Engineered Explosives
• 1 Mox Emerald
• 1 Mox Jet
• 1 Mox Pearl
• 1 Mox Ruby
• 1 Mox Sapphire
• 2 Sensei's Divining Top

Lands

• 4 Flooded Strand
• 1 Island
• 1 Library of Alexandria
• 2 Misty Rainforest
• 2 Polluted Delta
• 2 Tropical Island
• 2 Tundra
• 2 Underground Sea

(Not going to bother posting a sidebord since it's so metagame-dependent. In four colors there are a lot of options, though the deck really prefers to be in UW so I tend to prefer cards like Disenchant over Nature's Claim, for example, and I would definitely put a basic Plains in the board.)

I played an older (worse) version at Knight Ware a couple weeks back to mediocre results; I posted the old list, along with how I got from that to the new one, over here in a longer blog writeup. That post also has some sideboards in it.

Anyway, I'd be happy to get some feedback and thoughts on it.

(*) This is my first post on the new MD; I was a long-time lurker and very occasional poster on the old one.

Edited to tweak list formatting.

I like the idea of DRS as a mana creature and threat. I think that finding room for more Gush, cantrips, and perhaps probe would be good though.
I had a deck with Mentors, Probes, and Cabal Therapy before that was quite good at times.

Third Gush is definitely on the short list of things to fit in. I goldfished it with Probes but the life loss combined with Sylvan is really unmanageable vs any kind of life pressure. In theory DRS can gain life back but it isn't actually possible very often; green is the lowest-priority color in the deck so if I have a DRS out to make green for Sylvan Library, I'll almost never actually fetch up Trop.

This is an interesting list. I've seen some people like @Smmenen play a Fastbond+Tendrils mentor type list like this. If I'm swapping red for black, that's probably the direction I'd prefer to go. I'd definitely want to play Yawg Will and Fastbond at any rate given what your gameplan is, and at that point adding Tendrils comes at basically no cost.

But if you're trying to play a more fair game I do like DRS in theory against a lot of decks. I'm not sure if you're not playing Cruise because of Cut+Dig+DRS, but I'd honestly take Cruise over either Cut or DRS.

Yeah, if you add more black and Fastbond you can definitely go in a hybrid Storm-ish direction. I've seen a few lists like that and tried it myself. It's never quite come together for me so I decided to try out a more fair version.

The first version of the deck played Cruise instead of Cut; I'm testing Cut because that version desperately needed more removal, and I didn't feel like I needed both Cruise and Dig. It's quite possible that I should have cut Dig instead though, or that Cut just isn't worth it. I do like the idea of instant removal that can kill Lodestone Golem for 1 mana though.

Why cut? I play a 5 color mentor-gush-tendrils deck. Been in 1 tournament so far and if I hadn't made 2 large play errors (miscounting storm count against paul mastriano in game 3 and not being aggressive enough with a stolen hangarback walker against keith in game 1) I would have top 8'd with it at a 30+ person tournament. They were both later rounds and W in either round would put me in. I'm not going to post my deck list here because there are a few unique quirks to it that seem contradictory. I dont want to completely redirect the discussion.
But you easily take the a U/W mentor shell with a red splash for dack and some sideboard options against shops, B for tendrils/yawg will/demonic tutor and G for fastbond/sylvan library.

As for your specific decklist, I do have a question - what purpose does the deathrite shaman serve in this deck? It just seems like a slot that could be better served with any combination of more gushes, preordains, gitaxian probe, fastbond or even crypt and/or sol ring to help power out mentors faster.

The primary purpose of the Shamans is Wasteland resistance, but their incidental value in fighting Crucible, Snapcaster, Will, and JVP is not zero. It's not normally a card I'm a big fan of in Vintage (I generally think of it as "too fair") but it's been very useful in covering the third or fourth color.

I'm just not sure the fifth color is worth adding more fragility to the manabase; especially in a relatively fair list. I'm usually the first to climb aboard the Greed Train but in this case I'm happy to trade it for fewer games of getting randomly crushed by Shops, Landstill, or BUG Fish.