I think it would be easier to look at that list and offer a meaningful critique if you could tell us how you want the deck to function, how you designed it etc. You have tended to emphasize how well the deck works for you in actual play. That is fine, but it is easier for us to understand your choices if we know more about the deck.
It looks like you are trying to set up a self mill deck that does not use as many narrow combo only cards and generally has a robust board presence. For example, the crab really is the best self mill in the game. If you have crabs you will likely mill seance or RSD and can lean more heavily on that game plan.
Another way of looking at your deck is that it is a fatty deck with some graveyard support, which wouldn't want to devote slots to crab. With your high ratio of fat rescue from the underworld starts to look real good, you don't need so much self-mill if you are likely to mill a big fatty right off the bat.
Anyway the two previous examples were just meant to show ways that YOU could want your deck to work. You just posted your deck after a bunch of maniac builds, but it is clearly very different. An explanation is often more important than a decklist.
You make a good point. Alright, to better explain.
First I will start with the discussion on
Hedron Crab.
In the list I posted (note that I am not saying Crab is bad, or that it doesn't work in a GY deck, or anything silly like that), but in the list I posted, it feels completely and totally unnecessary.
Now Crab can work extremely well in these types of builds, but keep in mind WHY Crab works well. Because it mills so quickly.
Now take a look at my list and really ask yourself. Why do we need to mill ourselves that quickly? The real advantage of being able to mill yourself extremely quick is in using cards that actually benefit heavily from doing so.
As much as having a GY that is brimming with creatures is a good thing for cards like Seance and Sheoldred, outside of giving you some more options in WHAT to bring back, it doesn't do you nearly as much good as other GY based cards would in the same situation. Having a GY stocked for Seance/Sheoldred is nice, but they still only pull creatures out one at a time. I don't feel the need to have 3/4th of my deck in the GY for fuel for Seance/Sheoldred because outside of having a larger choice on what to bring back, what real purpose does it serve? Having 20 creatures in the yard doesn't do a whole lot to make Seance/Sheoldred better than having 10 creatures in the yard, because at most all we can bring back is 1 card per turn. As long as I have enough mill to make sure I can consistently bring back a card a turn with Sheoldred, or Seance (preferably on the opponents turn to be able to chump with the token as well) then I don't feel the need to continue milling ourselves, because it really isn't providing any extra value, outside of a larger choice on WHAT to bring back. Having more choices on what to bring back is obviously beneficial, but I don't believe it is worth it enough to go so deep into the mill plan.
Compare that with cards such as
Spider Spawning,
Laboratory Maniac and
Nemesis of Mortals these are the types of cards that REALLY benefit from the hyper mill plan. If I were running a deck based more around cards like these, then I probably WOULD be running Hedron Crab (and in fact, I have a Sultai self-mill deck that does). These are the types of cards that really benefit from milling yourself as quickly as possible. The difference between 10 and 20 creatures in the yard actually DOES make a huge difference with Spider Spawning, having 4 creatures instead of 2 makes a huge difference for Nemesis of Mortals, and of course milling yourself out quickly makes Lab Maniac a more reliable and consistent win-con.
We aren't running cards like that though. We also aren't going the traditional reanimator route with the deck where you cheat out fatties early and on the cheap using cards like
Rescue from the Underworld where we want to make sure that we stick a fattie in the yard ASAP to be able to cheat it out early. As such, we are less reliant on that quick mill, because we aren't looking to mill a fattie by T5 so we can cheat it out with Rescue.
Hence why I don't believe the hyper mill plan is worthwhile for this particular deck (although I do believe it is worth it in other decks, more built around taking advantage of it) and my previous comments about
Hedron Crab.
This list is pure and simple a value list. The deck isn't trying to go the tradition GY route, but instead uses the GY as another method of wringing out value. Basically everything we have gives us value in some form or another, be it getting played and chumping to go to the GY to be used later, or getting milled and pulled out to get value.
What this list (and lists like it) does best is the game of attrition. Because everything we have provides good value both when played, or when milled. This deck can literally stall all day long, even against large threats until it is able to set up the pieces it needs to just win on the spot.
While using the hyper mill strategy may provide us with a means of assembling those pieces somewhat faster/easier, it also cuts into our early game survival and the value in which we can get to carry us over into the late game.
I won't even begin to deny that when looking at the deck it looks like a total pile (mostly brought about by the curve being how it is), but I can promise you that if you put the deck together and take it online that you will be quite surprised by how well it actually does.
30 games so far with the deck online, and 27 wins.
The deck is literally a brick **** house when it comes to surviving through just about anything. So far the only issues I have had have come about from decks with a metric ton of cheap flyers which we have no real good defense against outside of trying to lifegain your way to dropping something like a Shadowborn/RSD to stabilize.
Keep in mind also that this deck originally spawned from my Abzan Seance deck, which would probably blow people mind to know uses
Satyr Wayfinder as its only source of self-mill, and is still able to keep cards like Seance and Sheoldred fully stocked to be able to do their thing.
The deck is built around value, it may be a GY deck, but the GY really isn't being used much more than for another source of getting that value. We aren't running cards like Seance and Sheoldred because we are actively TRYING to be a GY deck, we run them because they basically double the potential value of almost literally everything we are already running in the deck.
To be honest, unlike more traditional GY decks, we DON'T want to be milling our self unless we have to. As long as we have enough stock in the GY to keep Sheoldred going every turn, or to activate Seance on each of our opponents turns (to gain value and provide another chump for us) then there really isn't a huge point to continue to mill yourself.
The deck is much better served by actually DRAWING those cards first, playing them out to get said value, chumping with them, and THEN bringing them back to gain more value and chump again.
While every card we mill may be more gas for Sheoldred/Seance, it is also essentially halving the potential value of the card. A milled
Elvish Visionary will chump for us once and draw us a card. A drawn and played
Elvish Visionary on the other hand will chump for us twice, and draw us 2 cards.
Now I obviously know that milling our self is still worthwhile to do even with the loss of potential value because of the immediate value is provides, which is often a worthwhile tradeoff.
The line comes with how much you mill yourself though. As I said before, the difference between having 10 and 20 creatures in the yard for Seance/Sheoldred isn't really anything outside of variety of choice, because they only function once a turn (so can at most only pull out 1 creature at a time). At that point all we are doing by milling ourselves is throwing away potential value by not allowing ourselves to draw into the cards and play them out first before we start with the GY antics.
A case could still be made in that super milling yourself allows you to see more cards, so it is better served as a means of pulling individual pieces out of the deck when you really need them (Shadowborn when you need removal, RSD to fetch Craterhoof, Craterhoof itself, etc) which is certainly true, and not something I can deny at all.
I can say that the limited amount of mill the deck has has been enough for me thus far to still be able to pick out useful targets from the yard when I need too. Which is part of the reason I am still stuck on that singleton copy of
Dead Reckoning, since it functions for that exact purpose (and can be picked up with
Treasured Find in situations where we mill it itself).
So far the 30 games I have played with this deck I have lost to 2 U/W Skies decks and a Golgari Spawning deck that Craterhoofed me literally the turn before my own Craterhoof came down.