Alright, now that Bargain is unrestricted lets talk about this in the context of a TPS like ritual based Storm shell. Yawgmoth's Bargain is one of the most powerful draw engines ever printed, if not the most powerful if it is already on the battlefield. A resolved bargain often times can draw about 14 cards at instant speed, it clearly is cabaple as a central engine that can power the whole deck.
How many Bargains would you actually want to play? After drawing a single bargain, every other one you get is a dead card. I don't think playing a full playset is a good idea, even if you want to build a deck that relies on resolving one every single game. It clearly needs testing but 2 bargains in a shell with a bunch of tutors or 3 in a shell that really wants to draw one naturally, seems plausible.
How much life is there to pay? After the restriction of Gitaxian Probe i cut my Cabal Therapies from my Deck and replaced them with Thoughtseizes, i liked the change then, but in the context of a Bargain powered deck, iam not sure that i want to play about 2 thoughtseizes, paying 4 life, before resolving a bargain and drawing 4 less cards. How much life would you want to guarantee a win after resolving bargain, and how can we build the deck in a way that we always maximize the power of bargain by minimizing our life loss. A second Tenrils in the main is not unheard of, and this might come in handy as lifegain to set up a big Bargain powered turn. What can we replace the thought seizes with? More Defence Grids maindeck or maybe even Collective Brutality? The lifegain of the Collective brutality might even come in handy, and discarding extra Bargains is rarely a bad idea. 2 Mana for a discard spell is a ton though.
6 Mana is a lot, how can you modify the deck that you can reliably resolve a bargain in almost every situation? Since i havee put a playset of Dark Petition in my deck i upped the count of Cabal Rituals from 1 to 2. Bargain might demand to up the count to 3 or even to the full playset. What other options are there?
What to cut? If you want to build a deck for wich the main path to victory is via a Yawgmoth's Bargain, what do we not need anymore? Cutting expensive tutors might very well be the most obvious option. Drawing 12 cards in a turn should find you what you need without having to play 6 tutors in your deck. You also wouldn't need many tutors to find the bargain, if you have, lets say, 3 in the deck. I think cutting Dark Petitions is a possibility.
Apart from having to cast Bargain, which will use a lot of resources from a turn, you also would probably want to win in the very same turn. This is definitely possible if you have enough life left, but everybody knows the frustration of drawing 10 cards and then fizzling because you just didn't find mana and already used your landdrop. Since this will be our main path to victory how can we make sure that fizzling is as rarely a occurrence as possible.
A list could maybe look like this:
Mana sources (31)
This ofcourse is a very early draft and untested apart from gold fishing, what are your thoughts on this?
EDIT: i updated the decklist in this post.