Is this budgeted?

Somewhat, yes, at least in the sense that I won't be able to get things as expensive as cards like Thoughtseize and Cryptic Command.

What's our win con?

Delver of Secrets, Pack Rat, and Young Pyromancer

Three color delver strategies tend to play a slower game than plain U/R. Because of this in order to be competitive they get pushed into midrange. So keep that in mind when building and playing this. Now lets look at the deck. Dismember should not be a four of, especially with Terminate in the deck already. Go down to 1 Dismember and up two 3 Terminates. Fill the rest of the spots with two Thoughtseize. Since you are midrange Sleight of Hand is not the type of thing you want to be doing. Also you could use more counterspell, so add two Cryptic Commands. I know they are expensive but just wait till Modern Masters 2015 comes out and there price should drop for a short while. Drop a Gitaxian Probe and add two Tasigur, the Golden Fang. Also I would recommend a 2-2 split with Mana Leak and Remand. If any of this was unclear or just generally needs more explaining just tag me and I will get back to you. Cheers.

sirbar I currently don't have the third Terminate, but the end goal is a 4-2 split, Terminate to Dismember. Both Cryptic Command and Remand are cards I'm planning on picking up if/when they get price drops due to Modern Masters 2015, which I'm sure they will. Thoughtseize is a bit pricey, so I may wait for it to rotate out of standard before nabbing it, if I get it at all.

Tasigur, the Golden Fang has never amazed me, and even after seeing him played in similar lists, I always got the feeling that I would have preferred one of my other threats. But I guess there's a first time for everything, so I may proxy a couple copies and mess around with it.

I do have a question; in all my testing with this deck it seems to work quite well as an aggro deck, winning most of its games largely against midrange decks) quite quickly, so quickly that I moved Electrolyze out of the main board. So I guess my question is why should I move towards midrange? Granted my play group isn't even near indicative of a real Modern meta.

Anyways, thanks for all your feedback, it's much appreciated!

The whole point of playing the color over two color is that two color runs out of gas with out cruise. To prevent this you slow your have down with more removal and interaction as opposed to just air. Now this is not the same type of midrange as abzan too where you want to grind the game out but just to be conservative. Simply it's to win more games then the aggro plan would give you.

With the current build you are set more to aggro but proxy up the changes I suggested and you will tell the difference.

Sleight is a worse Telling Time. It's actually worse than even Anticipate.

malfeischylde, both Telling Time and Anticipate do cost an additional mana, and since this deck rarely goes above three lands in a game, it's hard to justify a ton of two and three mana spells. That said, Telling Time is a significant enough improvement that I may very well pick up a couple copies.

Yeah, I love telling time. It's one of the better draw/scry spells in the meta.

Why no Kolaghan's Command? It's really good. Maybe 2 command and 1 electrolyze? or just 3 command. Adding this means you might not need 2 Vandalblast in sideboard, and maybe just a Shatterstorm instead. I recommend Izzet Staticaster in the sideboard, it is so insane against a lot of decks. Rise/Fall is good too, but that's more in the controlling versions of Grixis, not sure about grixis delver.

What matchups are you having trouble with?

downie78 So... I don't know why I'm not running Izzet Staticaster in my sideboard, especially considering I have multiple copies just sitting around collecting dust. I want to run Shatterstorm over Vandalblast in my sideboard, however, I don't have any copies right now. I'm gearing up to order a bunch of cards, and I'm planning on getting a few copies of it.

In terms of Rise/Fall, I'm not in love with the card. I get that it's good, but I prefer it in a more controlling deck, and even there I don't think it's incredible. I run Grixis Control as well, and don't have any copies of it in that deck. As for Kolaghan's Command, I run two copies in the sideboard of Grixis Control, and should probably run 1-2 copies in this deck. I do prefer Electrolyze in this deck because it cantrips, which is important to ensure that I have things to do.

yeah fair points, and I guess in grixis control you're bringing back bigger threats like Jace, Vryn's Prodigy  ^Flip and Pia and Kiran Nalaar which makes Rise/Fall better. As for electrolyze vs k-command. K-command basically cantrips as well, since you're often either getting a creature back from your graveyard or making them discard a card which can be relevant. It is especially gross with Snapcaster.

Is Rakdos Charm mainly for twin decks? If so, Rending Volley might be a better option, being uncounterable.

Rakdos Charm is mainly for Twin but it has random applications against decks that take advantage of their graveyard as well as decks with dangerous Artifacts, like Affinity, so I like having that more than Rending Volley.

I'm not sure why you have 4 Young Pyromancers. Maybe cut 1 or 2 and add some gurmag anglers?