Flint Golem

Whenever this creature becomes blocked, defending player mills three cards.

Seal of Doom

Sacrifice this enchantment: Destroy target nonblack creature. It can't be regenerated.

Ruthless Cullblade

This creature gets +2/+1 as long as an opponent has 10 or less life.

Owlbear

Trample
Keen Senses — When this creature enters, draw a card.

Killing Wave

For each creature, its controller sacrifices it unless they pay X life.

Soul Manipulation

Choose one or both —
• Counter target creature spell.
• Return target creature card from your graveyard to your hand.

Serendib Efreet

Flying
At the beginning of your upkeep, this creature deals 1 damage to you.

Infiltrator's Magemark

Enchant creature
Creatures you control that are enchanted get +1/+1 and can't be blocked except by creatures with defender.

Pact Weapon

As long as this Equipment is attached to a creature, you don't lose the game for having 0 or less life.
Whenever equipped creature attacks, draw a card and reveal it. The creature gets +X/+X until end of turn and you lose X life, where X is that card's mana value.
Equip—Discard a card.

Shadowheart, Dark Justiciar

{1}{B}, {T}, Sacrifice another creature: Draw X cards, where X is that creature's power.
Choose a Background (You can have a Background as a second commander.)

Werewolf Pack Leader

Pack tactics — Whenever this creature attacks, if you attacked with creatures with total power 6 or greater this combat, draw a card.
{3}{G}: Until end of turn, this creature has base power and toughness 5/3, gains trample, and isn't a Human.

Three Tragedies

Shred Memory

Exile up to four target cards from a single graveyard.
Transmute {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Kathari Remnant

Flying
{B}: Regenerate this creature.
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Painbringer

{T}, Exile any number of cards from your graveyard: Target creature gets -X/-X until end of turn, where X is the number of cards exiled this way.

Soul Strings

Return two target creature cards from your graveyard to your hand unless any player pays {X}.

Mesmeric Fiend

When this creature enters, target opponent reveals their hand and you choose a nonland card from it. Exile that card.
When this creature leaves the battlefield, return the exiled card to its owner's hand.

Specter of Mortality

Flying
When this creature enters, you may exile one or more creature cards from your graveyard. When you do, each other creature gets -X/-X until end of turn, where X is the number of cards exiled this way.

Isleback Spawn

Shroud (This creature can't be the target of spells or abilities.)
This creature gets +4/+8 as long as a library has twenty or fewer cards in it.

Wavesifter

Flying
When this creature enters, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Evoke {G}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Slithery Stalker

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
When this creature enters, exile target green or white creature an opponent controls.
When this creature leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Persist

Return target nonlegendary creature card from your graveyard to the battlefield with a -1/-1 counter on it.

Pilfer

Target opponent reveals their hand. You choose a nonland card from it. That player discards that card.

Grave Consequences

Each player may exile any number of cards from their graveyard. Then each player loses 1 life for each card in their graveyard.
Draw a card.

Whirlermaker

{4}, {T}: Create a 1/1 colorless Thopter artifact creature token with flying.

The Wise Mothman

Flying
Whenever The Wise Mothman enters or attacks, each player gets a rad counter.
Whenever one or more nonland cards are milled, put a +1/+1 counter on each of up to X target creatures, where X is the number of nonland cards milled this way.