@Juggernaut-GO I'm in! But to @ChubbyRain 's point I think we might want to redirect the conversation. This thread should really just be called. How to beat Gush. Period.
The reason Mentor is so good is because Gush is so good. A mentor on a board where spells can't be played, or when it's controller is out of cards in hand, is just a Grey Ogre. Conversely, if one kills Mentors left and right, but doesn't deal with Gush and the other card drawing, "Mentor" decks will just run you out of cards and kill with any number of alternate kill conditions, or just the last mentor in their deck after the opponent's answers are gone.
Don't get me wrong on Mentor. It is crazy efficient, and incredibly dangerous. I really like it as a card. If actually broken, its probably the first white card since Balance that is. So thank you Wizards, thank you for giving Tundra a reason to live. But with that said, I just don't think Mentor is the problem, or the pressure point at which to attack a "Mentor" deck. Talk of sweepers is fine. One might need them to stay alive when a mentor hits the table, but keep in mind that these are for safety only. They will not win the game against Mentor the deck. One doesn't win the Daytona 500 by having the best seat belt. Mentor is only one card out of the Gush player's hand. It feels good to play a Supreme Verdict and know you're going to mop up a board of Mentor and his five students. It even feels like card advantage, but it isn't. That was Verdict trading for Mentor. One for one. If Gush continues to outdraw whatever you're playing... you're losing the Daytona 500.
The place to really attack Gush, is to attack the engine. Cards like Thalia, Sphere of Resistance, Thorn of Amethyst, Trinisphere, Chalice of the Void (to set at 1), Strip Mine, Wasteland, Notion Thief, Spirit of the Labyrinth, Chains of Mephistopheles are all really disruptive to Gush decks. Non-shops, non-hatebear decks should seriously be testing those cards as sideboard cards, if not finding decks to play them in the main. (I play Oath with a mainboard Chalice just to screw decks that run a bunch of 1 mana spells) As for sweepers, I like the ones that stick around on the board, like Engineered Plague and Dread of Night (though I like Dread less since it isn't a good sideboard card if they play Pyromancer, and because Misstep). Those can add up to real card advantage. If you're just using spells to reset the board, then it will come down to whoever draws more cards, and... oh yeah, they're playing Gush and we aren't. So... original problem. Also, the counter suite in Gush decks tends to have a lot of stuff that can't counter enchantments directly. (Flusterstorm and the like) So Gush decks have a harder time keeping that stuff off the board.
Lastly, and in light of the recent restrictions. Thank you for starting this thread. This is what should happen, instead of clamoring for rules changes or complaining about OP cards as if Gush is Ancestral Recall or something. We all know Gush is dangerous and widely played. There's always going to be a best deck, so if we aren't going to join them, let's get our crap together and beat them. I think Gush is a great deck, but if I knew the next tourney was going to be 90% Gush... then I like my chances. A predictable meta is a beatable meta.