Dargo, the Shipwrecker

As an additional cost to cast this spell, you may sacrifice any number of artifacts and/or creatures. This spell costs {2} less to cast for each permanent sacrificed this way and {2} less to cast for each other artifact or creature you've sacrificed this turn.
Trample
Partner (You can have two commanders if both have partner.)

Vicious Conquistador

Whenever Vicious Conquistador attacks, each opponent loses 1 life.

Sure Strike

Target creature gets +3/+0 and gains first strike until end of turn. (It deals combat damage before creatures without first strike.)

Blessing of Belzenlok

Target creature gets +2/+1 until end of turn. If it's legendary, it also gains lifelink until end of turn.

Cast Down

Mogis, God of Slaughter

Indestructible
As long as your devotion to black and red is less than seven, Mogis isn't a creature.
At the beginning of each opponent's upkeep, Mogis deals 2 damage to that player unless they sacrifice a creature of their choice.

Dutiful Return

Return up to two target creature cards from your graveyard to your hand.

Mind Rot

Bladebrand

Target creature gains deathtouch until end of turn.
Draw a card.

Play with Fire

Play with Fire deals 2 damage to any target. If a player is dealt damage this way, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Mishra's Factory

{T}: Add {C}.
{1}: Mishra's Factory becomes a 2/2 Assembly-Worker artifact creature until end of turn. It's still a land.
{T}: Target Assembly-Worker creature gets +1/+1 until end of turn.

Bone Shards

As an additional cost to cast this spell, sacrifice a creature or discard a card.
Destroy target creature or planeswalker.

Reckless Charge

Target creature gets +3/+0 and gains haste until end of turn.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mountain

Soul Bleed

Enchant creature
At the beginning of the upkeep of enchanted creature's controller, that player loses 1 life.

Kardur, Doomscourge

When Kardur, Doomscourge enters, until your next turn, creatures your opponents control attack each combat if able and attack a player other than you if able.
Whenever an attacking creature dies, each opponent loses 1 life and you gain 1 life.

Akoum Refuge

Akoum Refuge enters tapped.
When Akoum Refuge enters, you gain 1 life.
{T}: Add {B} or {R}.

Dual Shot

Dual Shot deals 1 damage to each of up to two target creatures.

Insatiable Hemophage

Mutate {2}{B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Deathtouch
Whenever this creature mutates, each opponent loses X life and you gain X life, where X is the number of times this creature has mutated.

Forerunner of Slaughter

Devoid (This card has no color.)
{1}: Target colorless creature gains haste until end of turn.

Stalking Predator

Menace (This creature can't be blocked except by two or more creatures.)
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Shady Traveler

Menace (This creature can't be blocked except by two or more creatures.)
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Shady Traveler // Stalking Predator

Breeches, Brazen Plunderer

Menace
Whenever one or more Pirates you control deal damage to your opponents, exile the top card of each of those opponents' libraries. You may play those cards this turn, and you may spend mana as though it were mana of any color to cast those spells.
Partner (You can have two commanders if both have partner.)