Solphim, Mayhem Dominus

If a source you control would deal noncombat damage to an opponent or a permanent an opponent controls, it deals double that damage to that player or permanent instead.
{1}{R/P}{R/P}, Discard two cards: Put an indestructible counter on Solphim, Mayhem Dominus. ({R/P} can be paid with either {R} or 2 life.)

Sek'Kuar, Deathkeeper

Whenever another nontoken creature you control dies, create a 3/1 black and red Graveborn creature token with haste.

Mayhem Devil

Whenever a player sacrifices a permanent, Mayhem Devil deals 1 damage to any target.

Henzie "Toolbox" Torre

Each creature spell you cast with mana value 4 or greater has blitz. The blitz cost is equal to its mana cost. (You may choose to cast that spell for its blitz cost. If you do, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)
Blitz costs you pay cost {1} less for each time you've cast your commander from the command zone this game.

Ognis, the Dragon's Lash

Haste
Whenever a creature you control with haste attacks, create a tapped Treasure token.

Crime Novelist

Whenever you sacrifice an artifact, put a +1/+1 counter on Crime Novelist and add {R}.

Mirkwood Bats

Flying
Whenever you create or sacrifice a token, each opponent loses 1 life.

Yurlok of Scorch Thrash

Vigilance
A player losing unspent mana causes that player to lose that much life.
{1}, {T}: Each player adds {B}{R}{G}.

Mahadi, Emporium Master

At the beginning of your end step, create a Treasure token for each creature that died this turn. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Lagomos, Hand of Hatred

At the beginning of combat on your turn, create a 2/1 red Elemental creature token with trample and haste. Sacrifice it at the beginning of the next end step.
{T}: Search your library for a card, put it into your hand, then shuffle. Activate only if five or more creatures died this turn.

Juri, Master of the Revue

Whenever you sacrifice a permanent, put a +1/+1 counter on Juri, Master of the Revue.
When Juri dies, it deals damage equal to its power to any target.

Hissing Miasma

Whenever a creature attacks you, its controller loses 1 life.

Riveteers Ascendancy

Whenever you sacrifice a creature, you may return target creature card with lesser mana value from your graveyard to the battlefield tapped. Do this only once each turn.

Kresh the Bloodbraided

Whenever another creature dies, you may put X +1/+1 counters on Kresh the Bloodbraided, where X is that creature's power.

Bloodletter of Aclazotz

Flying
If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

Bootleggers' Stash

Lands you control have "{T}: Create a Treasure token."

Blood Reckoning

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life.

Ziatora, the Incinerator

Flying
At the beginning of your end step, you may sacrifice another creature. When you do, Ziatora, the Incinerator deals damage equal to that creature's power to any target and you create three Treasure tokens.

Hissing Iguanar

Whenever another creature dies, you may have Hissing Iguanar deal 1 damage to target player or planeswalker.

Slimefoot and Squee

Whenever Slimefoot and Squee enters the battlefield or attacks, create a 1/1 green Saproling creature token.
{1}{B}{R}{G}, Sacrifice a Saproling: Return Slimefoot and Squee and up to one other target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Revenge of Ravens

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life and you gain 1 life.

Ashnod's Altar

Hissing Quagmire

Hissing Quagmire enters the battlefield tapped.
{T}: Add {B} or {G}.
{1}{B}{G}: Hissing Quagmire becomes a 2/2 black and green Elemental creature with deathtouch until end of turn. It's still a land.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Stalking Vengeance

Haste
Whenever another creature you control dies, it deals damage equal to its power to target player or planeswalker.