I like this.

Commanders

Edrica, Simic Prodigy
Legendary Creature - Human Wizard
When ~ enters the battlefield, create two 1/1 green ooze creature tokens.
: Until end of turn, target creature you control becomes a copy of another target creature you control.
2/2

Edrica, Simic Guildmaster
Legendary Creature - Human Mutant Wizard
Creature spells you control have flash.
Whenever a player casts a creature spell, you may tap target permanent and untap another target permanent.
4/4

Amon, the Envious
Legendary Creature - Human Warrior
At the beginning of each opponent's upkeep, if that player has more life than you, they lose 2 life and you gain 2 life. If they have more cards in hand than you, they discard a card and you draw a card. If they control a creature with greater power than any creature you control, they put a -1/-1 counter on one of them, and you put a +1/+1 counter on Amon.
3/3

Tacticians!

Izzet Tactician
Creature - Weird Soldier
Whenever ~ becomes blocked, draw a card.
: Switch ~'s power and toughness until end of turn.
1/5

Simic Tactician
Creature - Octopus Beast Soldier
~ can't be blocked by more than one creature.
: ~ gets +1/-1 or -1/+1 until end of turn
5/3

Boros Tactician
Creature - Minotaur Soldier
Menace
: Remove target creature blocking ~ from combat.
4/4

I just remembered the storyline bit from the original Innistrad block where Liliana forces Thalia to destroy the Helvault, and it gave me a great idea for how black could answer artifacts and enchantments within its flavor and color pie.

Necromancer's Edict
Sorcery
Target permanent's controller may sacrifice it. If they don't, they sacrifice X creatures instead.
"Your choice, cathar. You can give me what I want, or I can start taking away the things you want."

Also, a nice creature card I came up with.

Accursed Geographer
Creature - Human Wizard
, Sacrifice a creature: search your library for a basic land card, put it onto the battlefield tapped, then shuffle your library.
1/1
It's not ink those maps are written in.

And finally, a nice planeswalker idea I had:

Bog Entity
Enchantment - Aura Planeswalker
Enchant creature you control
{+1}: Enchanted creature gets +2/+2 until your next turn.
{-2} Enchanted creature deals damage equal to its power to target creature or planeswalker.
{-5} Sacrifice enchanted creature and draw five cards. Exile ~, then return it to the battlefield under your control.
{2}

Contrarion
Creature - Elemental
Flying
Whenever a player casts a spell, ~ gets -1/-1 until end of turn.
When ~ dies, you may counter target spell.
3/3

Avander Pondsage
Legendary Creature - Frog Wizard
Reach
Whenever you draw a card outside of your draw step, you may discard it. If you do, create a 3/3 blue and green frog creature token with reach.
, : Draw a card, then discard a card.
3/3
If you know what you like, why bother learning anything else?

Some disruption:

Secret Police
Creature - Human Soldier Rogue
When Secret Police enters the battlefield, name a nonland card.
Sacrifice Secret Police: Reveal the chosen card name and counter target spell with the chosen name.
2/2

Council Prohibitionists
Creature - Human Wizard
At the beginning of each opponent's draw step, look at that player's hand and name a nonland card. That player can't play spells of the chosen name until their next turn.
3/2

Garruk came back with M21, but there's a bit of a problem: Vivien already poached a lot of his existing design space while he was gone. So, what can he do now? Like all crazy roaming wilderness men, he must find wild, unexplored territory, untouched by any other walker. Here's some one idea:

Garruk, Savage Force
Legendary Planeswalker - Garruk
Garruk enters the battlefield with an additional loyalty counter for each creature you control with power 4 or greater.
{+1} Create a 4/2 green bear creature token.
{-4} Until end of turn, creatures you control gain ": This creature deals damage equal to its power to another target creature."
{-7} Search your library for a creature card, put it onto the battlefield, then shuffle your library. You get an emblem with "Creatures you control have hexproof and indestructible."
{3}

Sage of the Lost
Legendary Creature - Human Wizard Cleric
Whenever you cast a black spell, mill three cards and target player loses 1 life.
Whenever you cast a white spell, you may exile a creature card from your graveyard. If you do, create a 1/1 white spirit creature token with flying, and you gain 1 life.
1/3
"The past is lost, but not forgotten."

Make an Example
Instant
Destroy target creature. Tap each other creature that shares a controller with it.
"The sword is a mnemonic device for those who have forgotten their place"
Alek, Hand of Despots

Moonsilver Binder
Creature - Human Cleric
As ~ enters the battlefield, name a card.
: Counter target activated or triggered ability from a source with the chosen name.
1/2
"The cathars kill what fiends they can, and I bind those which they cannot."

Torturous Inquisitor
Creature - Human Wizard
When ~ enters the battlefield, look at target opponent's hand and choose a nonland card from it. That player discards that card unless they discard two cards.
3/2
"Is it really that important to you?"

A new take on an old walker:

Liliana, the Mind Warper
Legendary Planeswalker - Liliana
{+2} Look at the top card of target player's library. You may put that card into their graveyard.
{0} Exile target creature card from a graveyard and create a 2/2 black zombie creature token.
{-1} Target opponent reveals their hand and you choose a card from it. That player puts that card into their library second from the top.
{-12} Exile all cards from target player's library. Then, that player shuffles their graveyard into their library and discards their hand.
{3}

Some fun cards:

Arkbow Shot
Instant
Escalate
Choose one or more -
-Target creature gets +1/+1 and gains trample until end of turn.
-Target creature gains deathtouch until end of turn.
-Target creature gains indestructible until end of turn.
-Target creature you control fights another target creature.

Tamiyo's Scrollpack
Instant
Escalate
Choose one or more -
-Scry 1 and draw a card.
-Counter target spell unless its controller pays .
-Exile target permanent. Return it to the battlefield at the beginning of the next end step.

And a fun limited filler:

Stand Down
Instant
Return target creature you control and target creature an opponent controls to their owners' hands. Draw a card.

Yes I know it's just cantrip peel from reality but it's never been printed before and peel is a super neat effect but it's just not playable a lot of the time.

Unscrap
Sorcery
Return target artifact card with converted mana cost 3 or less from your graveyard to the battlefield.
Cycling

Unease
Enchantment
Opponents with two or fewer cards in hand can't cast spells.

Should maybe be partly white. It’s also a hard lock with any repeat discard (even if it said “one or fewer”) which I guess is intentional

The guy above who counters a spell when he dies is clever

More fun cards!

Spiteful Blow
Instant
As an additional cost to cast ~, sacrifice a permanent.
Destroy target permanent if it shares a card type with the sacrificed permanent.

Sword of Stone and Sunbeams
Artifact - Equipment
Equipped creature gets +2/+2 and has protection from colorless and multicolored. This protection doesn't remove ~.
Whenever equipped creature deals combat damage to a player, that player exiles a card from their hand or a permanent they control, and you may search your library for a basic land card, reveal it, and put it onto the battlefield tapped.
Equip

Oko, Fae Prankster
Legendary Planeswalker - Oko
{+1} Oko becomes a copy of target permanent until end of turn.
{-1} Create a 4/4 green bear creature token. Exile it at the end of your next turn.
{-4} Put a loyalty counter on target permanent. It becomes a copy of Oko.
{3}

Sheltering Greatbough
Creature - Treefolk
When Sheltering Greatbough enters the battlefield, create three 1/1 green squirrel creature tokens.
If a source would deal damage to a squirrel you control, you may have that source deal that much damage to ~ instead.
1/6