Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip

Whenever a black card is put into an opponent's graveyard from anywhere, you may draw a card.

Noncreature spells cost more to cast.

, , Discard a card: Destroy target artifact or enchantment.

Flying
When this creature enters or dies, exile target permanent.

Flying
You and Humans you control have hexproof.
, Exile a card from your graveyard: Create a 1/1 white Human Soldier creature token.

, : Roll a d20 and subtract the number of cards in your hand. If the result is 0 or less, discard your hand.
1—9 | Return a card at random from your graveyard to your hand.
10—19 | Draw two cards.
20 | Put a creature card from any graveyard onto the battlefield under your control. When that creature dies, its owner loses the game.

: Add one mana of any color that a land an opponent controls could produce.

This creature gets +1/+1 for each other creature on the battlefield named Relentless Rats.
A deck can have any number of cards named Relentless Rats.

At the beginning of your upkeep, if you have 5 or less life, sacrifice this enchantment and take an extra turn after this one.

Flying, trample
Pay 2 life: Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

For each creature target player controls, create a token that's a copy of that creature, except it has haste and "At the beginning of the end step, if you don't control a planeswalker, sacrifice this creature."

Negative — As long as K-9 is untapped, other legendary creatures you control have ward .
Affirmative — , : Target legendary creature can't be blocked this turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)

At the beginning of your upkeep, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this token: Draw a card.")
, Sacrifice three Clues: Search your library for a card, put that card into your hand, then shuffle.

Draw a card for each creature you control.
Ferocious — You gain 4 life for each creature you control with power 4 or greater.

Cast this spell only during combat.
Untap target creature you don't control and gain control of it. It gains haste until end of turn. At the beginning of the next end step, sacrifice it. If you do, you gain life equal to its toughness.

Landfall — Whenever a land you control enters, add one mana of any color.

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever a creature you control with deathtouch deals combat damage to a player, that player gets two poison counters. (A player with ten or more poison counters loses the game.)

At the beginning of each player's upkeep, that player may put an artifact, creature, or land card from their hand onto the battlefield.

Flying
Creature spells with flying you cast cost less to cast.
Whenever another creature you control with flying enters, this creature gets +1/+1 until end of turn.