Ob Nixilis, Unshackled

Flying, trample
Whenever an opponent searches their library, that player sacrifices a creature of their choice and loses 10 life.
Whenever another creature dies, put a +1/+1 counter on Ob Nixilis, Unshackled.

Mindlock Orb

Rest in Peace

When Rest in Peace enters, exile all graveyards.
If a card or token would be put into a graveyard from anywhere, exile it instead.

Darksteel Mutation

Enchant creature
Enchanted creature is an Insect artifact creature with base power and toughness 0/1 and has indestructible, and it loses all other abilities, card types, and creature types.

Zur, Eternal Schemer

Flying
Enchantment creatures you control have deathtouch, lifelink, and hexproof.
{1}{W}: Target non-Aura enchantment you control becomes a creature in addition to its other types and has base power and base toughness each equal to its mana value.

Blind Obedience

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Hushbringer

Flying, lifelink
Creatures entering or dying don't cause abilities to trigger.

Zur the Enchanter

Flying
Whenever Zur the Enchanter attacks, you may search your library for an enchantment card with mana value 3 or less, put it onto the battlefield, then shuffle.

Glacial Chasm

Cumulative upkeep—Pay 2 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Glacial Chasm enters, sacrifice a land.
Creatures you control can't attack.
Prevent all damage that would be dealt to you.

Spirit of the Labyrinth

Each player can't draw more than one card each turn.

Opposition Agent

Flash
You control your opponents while they're searching their libraries.
While an opponent is searching their library, they exile each card they find. You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them.

Linvala, Keeper of Silence

Flying
Activated abilities of creatures your opponents control can't be activated.

Fog Bank

Defender (This creature can't attack.)
Flying
Prevent all combat damage that would be dealt to and dealt by this creature.

Hushwing Gryff

Flash
Flying
Creatures entering don't cause abilities to trigger.

Eidolon of Rhetoric

Each player can't cast more than one spell each turn.

Statecraft

Prevent all combat damage that would be dealt to and dealt by creatures you control.

Fall of the Thran

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Destroy all lands.
II, III — Each player returns two land cards from their graveyard to the battlefield.

Ward of Bones

Each opponent who controls more creatures than you can't cast creature spells. The same is true for artifacts and enchantments.
Each opponent who controls more lands than you can't play lands.

Aminatou, the Fateshifter

+1: Draw a card, then put a card from your hand on top of your library.
−1: Exile another target permanent you own, then return it to the battlefield under your control.
−6: Choose left or right. Each player gains control of all nonland permanents other than Aminatou, the Fateshifter controlled by the next player in the chosen direction.
Aminatou, the Fateshifter can be your commander.

Thalia, Heretic Cathar

First strike
Creatures and nonbasic lands your opponents control enter tapped.

Containment Priest

Flash
If a nontoken creature would enter and it wasn't cast, exile it instead.

Archivist of Oghma

Flash
Whenever an opponent searches their library, you gain 1 life and draw a card.

Lavinia, Azorius Renegade

Each opponent can't cast noncreature spells with mana value greater than the number of lands that player controls.
Whenever an opponent casts a spell, if no mana was spent to cast it, counter that spell.

Isochron Scepter

Imprint — When Isochron Scepter enters, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Counterspell

Lifetap

Whenever a Forest an opponent controls becomes tapped, you gain 1 life.

Frozen Aether

Artifacts, creatures, and lands your opponents control enter tapped.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Ankh of Mishra

Whenever a land enters, Ankh of Mishra deals 2 damage to that land's controller.

Darkness

Prevent all combat damage that would be dealt this turn.

Armageddon

Rule of Law

Oloro, Ageless Ascetic

At the beginning of your upkeep, you gain 2 life.
Whenever you gain life, you may pay {1}. If you do, draw a card and each opponent loses 1 life.
At the beginning of your upkeep, if Oloro, Ageless Ascetic is in the command zone, you gain 2 life.