Sir_Crow

Hell's Caretaker might a substitute for recurring nightmare. I like Skinrender for "enter the battlefield destroy"

I would say that VintageFTW is wrong as the Oracle text on Gatherer reads "Untap horseshoe crab", this ability can only untap a creature named horseshoe crab

I am wondering, why Tormented Hero? I don't see anything to activate him with.

It might be a good idea to have Dueling Grounds instead of Silent Arbiter

I would replace, Whitesun's Passage with Life Burst, it is capable giving more life in the long run.

Ooze flux is amazing with undying, i use it in my undying deck

Read a Little closer, Isochron Scepter only works with instants not sorceries

You have way to many expensive cards, any normal deck will not give you the chance to get the big dragons on the table.

I have seen Invigorate being used for great effect in a similar deck.

A few Cabal Coffers can be very effective with Korlash also Exsanguinate can be a powerfull finisher

Do you have a plan for dealing with an opponents graveyard removal in the current climate with both rest in peace and groundseal, both of which black can't deal with.

I like the deck, i would perhaps have ward sliver in SB instead of muscle sliver that you can't hav anyway. A comment on your strategy description the poisonus ability gives the opponent 1 poison counter for each time they are dealt damage not 1 for every point of damage so magma sliver will not effect virulent slivers ability. If were playing the deck i would change magma sliver for crystaline sliver as your slivers will likely be shot at from the start of the game, it would also be a good idea to have winged sliver in SB or maybe put shifting in SB and winged in MB as it can in many circumstances can give you the same advantage for a lower mana cost

While i do agree that the sivers are meant to share abilities with each other having to many different can put you in a disavantage for if a sliver you need on the table gets shot you have less of the chance to draw it again draw spell or not. As for sliver cycling, it is a good ability to be sure, but it also show your opponant what you get and basing your strategies on revealed cards can be risky. Last but not least, there are plenty of good slivers with abilities that stack the more you have and even if you draw one you already have on the table it is often a good idea to have a replacement for sliver have a tedency to attract burn and destroy magic.

I would say remove get rid of half the different types of sliver you have and have 3-4 of the remaining, if you have to many different the deck becomes to random in what you draw it is much better to focus on a single strategy and make that one good instead of trying to embrace to many different ways of winning, i have run my own sliver deck for about 7 years it is built sliver that pump and evasiton mostly through ward sliver.

Im thinking maybe "No rest for the wicked" or "Shirei, Shizo's Caretaker"

Immaculate Magistrate is very powerful with the warcaller

Gravecrawler is an obvious choice fore a zombie deck as it can be used to fuel the many powerful effects black has that require sacrifices, i use it to great effect with attrition and mindslash. A lesser known card is Gempalm Polluter which is an good way to draw cards in zombie decks and it can deal a lot of damage with army of the damned. Lord of the Undead is also worth considering as he lets you use your zombies again endlessly

The deck is way too spred out, focus on fewer different creatures, to win you need a strategy, that however is almost impossible to achieve if yourdeck is too varied for you will never have any idea of what you are going to draw, and while having a lot of different opitions is a good idea, having to many impedes your ability to win because chances are you wont get the card you need.

In my opinion no RB deck is complete without terminate

Red madness spells like Fiery Temper works well with Chandra Ablaze.