Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Teysa Karlov

If a creature dying causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Creature tokens you control have vigilance and lifelink.

Sol Ring

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Blood Artist

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

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")