MTG Salvation

Life from Death
Sorcery
Life from Death is black.
As an additional cost to play Life from Death, reveal a Druid card from your hand or pay :symb:.
Return target creature card from your graveyard to your hand.

Ghazbani Hex
Enchantment - Aura
Enchant creature
At the beginning of your upkeep, if a player has more life than any other, that player gains control of enchanted creature.

Font of Knowledge
Enchantment
If you would draw a card, you may discard a card instead. If you do, draw two cards.
Untold knowledge always comes with such a headache.

Tax Collector :2mana::symw:
Creature - Human Advisor
Whenever an opponent plays a spell, put a +1/+1 counter on Tax Collector unless that player pays :1mana:.
1/1

Old Chomper :2mana::symb::symr:
Legendary Creature - Lizard
Haste, lifelink
As the Saurians grow older, they become meaner and fouler tempered. If any of them are older than Old Chomper himself, he must've eaten them a long time ago.
4/4

Quote from Sutherlands

As has been said, the chosen abilities just aren't representative of their colors, even if they do appear in those colors.

Sutherlands: The very point of reshuffling the abilities was to make it so that cycles would be easier to create like this. If you recall, he brought up the explicit problem of rare cycles; blue would always end up with flying, which in turn made everything else fall into place.

Just because this isn't how things have been done in the past doesn't mean this isn't how things will be done going forward.

Trueshot Archer :1mana::symgu:
Creature - Human Archer
Whenever you draw a card, Trueshot Archer gets +1/+1 until end of turn.
1/1

Statistically speaking, Raise or Fold will have the following effects in an average deck [An average deck is defined as having 24 lands, because it's really easy to do the math for and is, in fact, a good number]:

Choose 5: Reveal 3 nonland, 2 land. You draw 3 cards and lose 15 life. (Remember, you pay X life and then lose X life for each land revealed.)

Choose 4: Reveal 2 nonland, 2 land. You draw 2 cards and lose 12 life.

Choose 3: Reveal 2 nonland, 1 land. You draw 2 cards and lose 6 life.

Choose 2: Reveal 1 nonland, 1 land. You draw 1 card and lose 4 life.

Choose 1: Reveal 1 nonland. You draw 1 card and lose 1 life.

Personally, I think it looks balanced in any of its incarnations. My mian issues with it are how swingy it is (deviating from the norm happens quite a bit, resulting in either immediately losing the game or drawing 5 for 1B) and how confusing the wording can be (it is not immediately obvious from the wording that you lose nx life, where x is chosen by the player and n is 1 + the number of lands revealed).

Phoenix Hatchling :1mana::symrw:
Creature - Phoenix
Flying
At the beginning of your upkeep you may pay :symrw:. If you do, return Phoenix Hatchling from your graveyard to your hand.
1/1

I like the red proof basing on lands, although it would be more red to focus on nonbasics. The main issue with that is that the proofs cost four mana, and people tend not to be holding too many lands at that point outside of Limited. (Although nonbasics would at least make "Decadence" a fitting name). I dunno, I'm just opposed to making a card do something to match a cycle when it doesn't have to. If you need to force a line of text onto a card to make it fit your cycle, you should probably evaluate if it should be in the cycle.

Black: Black does have some options, I suppose. You could aim for a mirror to white:

Proof of Corruption :3mana::symb:
Sorcery (U)
You and target opponent reveal your hands. Then if that player has more black cards in hand than you...

The issue with that would be that it will almost never work, making it really rather narrow in usage. Of course, most of my other immediate ideas are even more narrow, so...

Quote from Valros

And Finish Him!, while probably unfun if you get hit by it, also requires these things:

- You must have at least twice your opponent's life total, plus 2 life.
- You must have a card of significant CMC on the top of your library.
- The opponent must lack lifegain (or countermagic, but that is usually a requirement of any combo)
- The opponent must lack a card of significant CMC on the top of his or her library.

Granted, black (and blue) can guarantee a lot of that, but it needs a good supporting cast. And in the set that I'm putting this in, every color has some access to clash-based or scry-based action, and library manipulation is pretty common.

It doesn't matter if a card is balanced if it isn't fun. Requiring a bunch of things to go off with it does not change the fact that people will randomly lose the game to it. =/

Also, I don't much like Proof of Heresy. The number of times you won't win that one in the deck it would be played in would be...?

Also, what's the point in revealing your hand for Proof of Decadence? All you're doing is counting cards. You're not even looking for cards of a specific quality.

Mourning Shroud :1mana::symwb:
Enchantment - Aura
Enchant creature
Enchanted creature gets +1/+1 and gains lifelink.
:symwb:, sacrifice enchanted creature: Attach Mourning Shroud to target creature you control.
As the plague spread, only a small handful of people were left uninfected. Most of them spent their days caring for the ill until they, too, wasted away.

Restraining Order :1mana::symw:
Instant
You may remove two white cards in your graveyard from the game rather than pay Restraining Order's mana cost.
Prevent all damage target creature would deal this turn.

Ninja of Shifting Sands :1mana::symw::symw:
Creature - Fox Ninja
Ninjutsu :1mana::symw:
Whenever ~ deals combat damage to a player, you may tap target creature. If you do, it doesn't untap during its controller's next untap step.
In one twisted version of Kamigawa, Konda's law was enforced by shadowy assassins.
2/2

Typhon, the Last Challenger :symb::symb::symr::symr:
World Creature - Titan
(When a World permanent comes into play, put all other World permanents into their owner's graveyard.)
Haste
Whenever Typhon, the Last Challenger deals combat damage to a creature or player, it deals that much damage to target creature or player.
3/3