Ayara's Oathsworn

Menace
Whenever Ayara's Oathsworn deals combat damage to a player, if it has fewer than four +1/+1 counters on it, put a +1/+1 counter on it. Then if it has exactly four +1/+1 counters on it, search your library for a card, put it into your hand, then shuffle.

Homicide Investigator

Whenever one or more nontoken creatures you control die, investigate. This ability triggers only once each turn. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Go for the Throat

Tenacious Underdog

Blitz—{2}{B}{B}, Pay 2 life. (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)
You may cast Tenacious Underdog from your graveyard using its blitz ability.

Ashnod, Flesh Mechanist

Deathtouch
Whenever Ashnod, Flesh Mechanist attacks, you may sacrifice another creature. If you do, create a tapped Powerstone token.
{5}, Exile a creature card from your graveyard: Create a tapped 3/3 colorless Zombie artifact creature token.

Festerleech

Whenever Festerleech deals combat damage to a player, you mill two cards.
{1}{B}: Festerleech gets +2/+2 until end of turn. Activate only once each turn.

Restless Reef

Restless Reef enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}: Until end of turn, Restless Reef becomes a 4/4 blue and black Shark creature with deathtouch. It's still a land.
Whenever Restless Reef attacks, target player mills four cards.

Darkslick Shores

Darkslick Shores enters tapped unless you control two or fewer other lands.
{T}: Add {U} or {B}.

Transmogrant's Crown

Equipped creature gets +2/+0.
Whenever equipped creature dies, draw a card.
Equip {2} or {B}

Scorn-Blade Berserker

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
{1}, Sacrifice this creature: Draw a card.

Undercity Sewers

({T}: Add {U} or {B}.)
Undercity Sewers enters tapped.
When Undercity Sewers enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Cult Conscript

Cult Conscript enters tapped.
{1}{B}: Return Cult Conscript from your graveyard to the battlefield. Activate only if a non-Skeleton creature died under your control this turn.

Phyrexian Obliterator

Trample
Whenever a source deals damage to Phyrexian Obliterator, that source's controller sacrifices that many permanents of their choice.

Infernal Grasp

Destroy target creature. You lose 2 life.

Mukotai Soulripper

Whenever Mukotai Soulripper attacks, you may sacrifice another artifact or creature. If you do, put a +1/+1 counter on Mukotai Soulripper and it gains menace until end of turn.
Crew 2 (Tap any number of creatures you control with total power 2 or more: This Vehicle becomes an artifact creature until end of turn.)

Hunted Bonebrute

Menace
When Hunted Bonebrute enters, target opponent creates two 1/1 white Dog creature tokens.
When Hunted Bonebrute dies, each opponent loses 3 life.
Disguise {1}{B}

The Mycosynth Gardens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{X}, {T}: The Mycosynth Gardens becomes a copy of target nontoken artifact you control with mana value X.

Swamp

Evolved Sleeper

{B}: Evolved Sleeper becomes a Human Cleric with base power and toughness 2/2.
{1}{B}: If Evolved Sleeper is a Cleric, put a deathtouch counter on it and it becomes a Phyrexian Human Cleric with base power and toughness 3/3.
{1}{B}{B}: If Evolved Sleeper is a Phyrexian, put a +1/+1 counter on it, then you draw a card and you lose 1 life.