Sultai STD

You stated that this is a standard deck, so I'm going to assume that your end goal would be to take it to an FNM and not just get totally destroyed every game.  Please correct me if I'm wrong here.

That being said, I'm seeing quite a few conflicting elements here that I think will make this a bit underwhelming:

1) You have TONS of stuff to fill the yard and seem to have gone overboard with the delve option, but not all of the pieces fit together that seamlessly.  From a quick look through, it seems that the primary win con is to cheat out a Necropolis Fiend for relatively cheap.  Is this correct?  Sidisi really doesn't flood the board as much as you'd think given the current creature count and the number of tools that fill the yard multiple cards at a time.  If this is the case, I think you're REALLY going to struggle in a more competitive environment - specifically, I can easily see where a single Elspeth, Sun's Champion could just stone-wall you.

2) Where's the sideboard?

3) Several of the cards here are highly counter-productive or otherwise just don't really go with a single focused plan.  For instance, Pharika requires you to have creatures in the yard to really impact the board, but delve will, by definition, remove those creatures.  As another example, Villainous Wealth practically demands a strategy utilizing some sort of ramping to then cast it for a large total... yet, you have no ramp here AND will likely be shedding a LOT of your lands to the yard with all the stuff you're using to fill the yard.

4) The mana-base is SLOW and doesn't even have the advantages of scry lands.  Seriously, where are the Theros block pieces?  If you just started that's fine, but they're going to be pretty important to be competitive.  The M15 pain-lands can also be a great help here, even as 1-2x of each (Yavimaya Coast and Llanowar Wastes in case you didn't already know).

So, where do you go from here?  Well, luckily there are plenty of options:

1) Go for a more ramp-centric build that really focuses on Villainous Wealth and a few other bombs - for this keep your eyes on Travis Woo's posts over at Channel Fireball as he's pretty interested in doing just this type of thing (and has even said so himself).

2) Have a bit of fun with Sidisi and toss a few delve pieces in there for a good time.  Note that this strategy requires nowhere even close to the amount of digging you have currently in your deck.  To do this sort of thing I would advocate for Sylvan Caryatid, Courser of Kruphix (if you can get them), and things of that nature.  I actually have been playing with a build based around Sidisi and some funny interactions and it has performed alright (not perfectly, but it wins more than it loses).  You can see that build here: https://deckbox.org/sets/788285  Amusingly enough Omenspeaker and Dakra Mystic have been absolute all-stars for me as they let you fix your draws while letting you screw up an opponent (if they have a Courser in play, you can literally control their draws to some extent) AND offering a nice card-by-card way to trigger Sidisi.

3) Go with some sort of a reanimator build.  For these I would look to the recent SCG results that had some of these elements.  Here the key really is Whip of Erebos and the flexibility it provides you to reanimate your stuff.  Sidisi milled that Abhorrent Overlord off the top of your deck?  What a shame, now you can reanimate it for four, get five harpy tokens, and swing with a 6/6 flying lifelink.  Note that people doing this have been using white so they can utilize Ashen Rider from Theros as an absolute reanimation bomb - something you could still do here as you will frequently mill them to the yard and can also use Sultai Charm to drop the ones you draw.

4) Go with a yard filling strategy not unlike Conley Woods' B/G dredge deck from before rotation.  You pick up a few added pieces with the delve that will make the deck a bit more potent (card draw, Murderous Cut, etc.).  The key here is not to load up too heavily on the delve cards.  I think the big mistake you're making at the moment here is having too many delve cards in the build... think about it, you can cast Dead Drop for B and exile 9 cards from your yard, but what about that second copy in your hand?  Now you have a REALLY overcosted card that you're spending your turns filling the yard just to cast.  Anyway, google Conley Woods B/G dredge and see if that's more up your alley.

I hope some of this mess helps.  I'd be happy to explain anything you're confused with or aren't following further.  Good luck!

Also note, I am playing casually more than competitive