Sylvan Advocate is a card rarely excluded from green decks, especially when you have access to 8 manlands AND will hit your 6th land drop nearly every game. After testing and seeing how games played out, I am casting Languish on T4/T5 most games. That combined with the fact that it always dies to the return side of Kozilek's Return lead me away from playing the card.
Tireless Tracker suffers nearly the same fate as Sylvan Advocate. I am hitting all of my lands and playing evolving wilds, but the fact that it just dies to so much of what I am doing is just depressing. It's possible one copy is interesting in case I flood late and can tutor for it, but if I'm flooding and can use Traverse the Ulvenwald then I can just get Emrakul, the Promised End
Grasp of Darkness (and other good removal) is extremely well positioned against a large portion of the field. There would be a way to reconfigure the mana to play it, but overall I felt it was unnecessary to be playing removal with 3 Languish and 3 Kozilek's Return
Gather the Pack would be an additional engine in this deck that actually works with Jace, Vryn's Prodigy
. The inability to grab lands is a problem, and, with 19 creatures, hitting two isn't even that likely. I also don't feel like I need additional effects like this, and Vessel of Nascency is an enchantment for delirium, which I think is better.
Learn from the Past for opposing Emrakul, the Promised End decks and the zombie decks, this seems like it's a good idea. Overall, I really just can't seem to find room. It's not amazing against temurge even, which is why I ended up cutting it. If you expect to see zombie decks, include two in the board for sure!
Caustic Caterpillar is an answer to Demonic Pact, Pyromancer's Goggles, and other problem artifacts and enchantments. Since we can tutor for it and reuse it many times, it's a card that would be good in the board. I would include this for FNM, but not a highly competitive tournament where I expect the meta to be less diverse.
Distended Mindbender I THOUGHT was going to be better than the 3rd Elder Deep-Fiend in this deck. The ability to tutor for a double discard effect, or simply do it on turn 4 is very good. Especially with all these other Grapple with the Past decks, sometimes you know there's a card you need to take. Overall, I wanted the deck to be more streamlined with 3 elder deep-fiends because flash, the 5/6 body, and the ability to loop them is very good. I like having access to this effect, but I just couldn't fit it anywhere. Additionally, in the matchups where it's good, they are either not tier1 decks, or they play Kozilek's Return. I have better cards against those decks in the board anyways.