Interesting idea you have here. There are definitely a couple of things that have to be worked out here:
0. Before anything else, you must know that
dash hopes is widely regarded as a bad magic card, because your opponent will always pay the 5 life if they want the spell to resolve, or let the spell get countered if they need the life. Pull these cards. Just trust me.
1. Keep in mind that the modern format has MANY non-creature decks and recurring creature deck. The former, and often the latter, are COMPLETELY UNAFFECTED by the deck's
game plan. This means you will want to include one or two cards that get better if they are on the board unopposed, or that hate on spell-based strategies (like discard spells.
Inquisition of kozilek is pretty cheap)
2. This also means pulling any cards that do nothing without an opponent having creatures. This means
contagion clasp and
grim affliction have got to go. This is of course not the case if you want to add another kind of counter to be proliferating, but this is likely not the right direction.
3. Speaking of a lack of creatures: You only run 4 yourself! Sure, it's a very cool creature, but wouldn't it be nice if he had some friends? To add insult to injury, you also play 6 spells that pump creatures in your favor, and they are lonely because they have no targets. This
simple solution here is to cut the pump spells for some creatures. First strike or double strike creatures are especially desirable because when given wither, the opposing creature will have its power decreased before it gets to hit back, increasing the likelihood your guy survives.
4.
Diabolic tutor is too slow for modern. Many decks will kill you turn 4. Same issue goes for
torment of venom, as well as the fact that it gives the opponent a choice just like
dash hopes.
So with that, the following cards in you deck remain:
4
Corrosive mentor4
Nest of scarabs4
Shadows of the past (good for fixing draw quality and can end a game given enough time. Cool choice!)
4
Grasping dunes4
Ifnir deadlands12
SwampI know this isn't much, but the point I am trying to make is that your engine of mentor + nest is a very good start. You just need to place better cards around it. I suggest searching the entirety of the modern format (I notice everything you have here is only standard, lorwyn, or shadowmoor) and see what kind of -1/-1 synergies you can find. The best kind of thing would be a card that puts -1 counters in a creature every upkeep. You are also gonna want to find cards that are just plain good. Good cards win games. I encourage you to make sure these cards blend well with your original engine, or even add to it, but this isn't always necessary.
I really hope you find this helpful. Good luck!