Altar of Dementia

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

Sidisi, Brood Tyrant

Whenever Sidisi, Brood Tyrant enters or attacks, mill three cards.
Whenever one or more creature cards are put into your graveyard from your library, create a 2/2 black Zombie creature token.

Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Ikra Shidiqi, the Usurper

Menace
Whenever a creature you control deals combat damage to a player, you gain life equal to that creature's toughness.
Partner (You can have two commanders if both have partner.)

Ramunap Excavator

Sultai Soothsayer

When Sultai Soothsayer enters, look at the top four cards of your library. Put one of them into your hand and the rest into your graveyard.

Naga Vitalist

{T}: Add one mana of any type that a land you control could produce.

Weaver of Currents

Sidisi's Faithful

Exploit (When this creature enters, you may sacrifice a creature.)
When Sidisi's Faithful exploits a creature, return target creature to its owner's hand.

Sultai Ascendancy

At the beginning of your upkeep, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Sidisi, Undead Vizier

Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When Sidisi, Undead Vizier exploits a creature, you may search your library for a card, put it into your hand, then shuffle.

Taigam, Sidisi's Hand

Skip your draw step.
At the beginning of your upkeep, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
{B}, {T}, Exile X cards from your graveyard: Target creature gets -X/-X until end of turn.