Snapcaster Mage

Flash
When this creature enters, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Karoo

This land enters tapped.
When this land enters, sacrifice it unless you return an untapped Plains you control to its owner's hand.
{T}: Add {C}{W}.

Lotus Field

Hexproof
This land enters tapped.
When this land enters, sacrifice two lands.
{T}: Add three mana of any one color.

Tale's End

Counter target activated ability, triggered ability, or legendary spell.

Eater of Days

Flying, trample
When this creature enters, you skip your next two turns.

Giver of Runes

{T}: Another target creature you control gains protection from colorless or from the color of your choice until end of turn.

Adric, Mathematical Genius

{2}{U}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
Ultimate Sacrifice — {1}{U}, Sacrifice Adric: Counter target activated or triggered ability.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Denizen of the Deep

When this creature enters, return each other creature you control to its owner's hand.

Intervention Pact

The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.
At the beginning of your next upkeep, pay {1}{W}{W}. If you don't, you lose the game.

Azorius Chancery

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Strict Proctor

Flying
Whenever a permanent entering causes a triggered ability to trigger, counter that ability unless its controller pays {2}.

Jokulmorder

Trample
This creature enters tapped.
When this creature enters, sacrifice it unless you sacrifice five lands.
This creature doesn't untap during your untap step.
Whenever you play an Island, you may untap this creature.

Sister of Silence

Flash
Psychic Abomination — When this creature enters, counter target instant spell, sorcery spell, activated ability, or triggered ability.

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Angelic Intervention

Target creature or planeswalker you control gains protection from colorless or from the color of your choice until end of turn. If it's a creature, put a +1/+1 counter on it. (It can't be blocked, targeted, dealt damage, enchanted, or equipped by anything with that quality.)

Faerie Impostor

Flying
When this creature enters, sacrifice it unless you return another creature you control to its owner's hand.

Hushbringer

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

Hushwing Gryff

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

Glint Hawk

Flying
When this creature enters, sacrifice it unless you return an artifact you control to its owner's hand.

Overcharged Amalgam

Flash
Flying
Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, counter target spell, activated ability, or triggered ability.

Disallow

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Torpor Orb

Creatures entering don't cause abilities to trigger.

Stifle

Counter target activated or triggered ability. (Mana abilities can't be targeted.)

Quickling

Flash (You may cast this spell any time you could cast an instant.)
Flying
When this creature enters, sacrifice it unless you return another creature you control to its owner's hand.

The Eighth Doctor

When The Eighth Doctor enters, mill three cards.
Once during each of your turns, you may play a historic land or cast a historic permanent spell from your graveyard. If you do, it gains "If this permanent would leave the battlefield, exile it instead of putting it anywhere else."

Coral Atoll

This land enters tapped.
When this land enters, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.

Sublime Epiphany

Choose one or more —
• Counter target spell.
• Counter target activated or triggered ability.
• Return target nonland permanent to its owner's hand.
• Create a token that's a copy of target creature you control.
• Target player draws a card.

Trickbind

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Counter target activated or triggered ability. If a permanent's ability is countered this way, activated abilities of that permanent can't be activated this turn. (Mana abilities can't be targeted.)

Tocatli Honor Guard

Guildless Commons

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {C}{C}.

Defabricate

Choose one —
• Counter target artifact or enchantment spell. If a spell is countered this way, exile it instead of putting it into its owner's graveyard.
• Counter target activated or triggered ability.

Phyrexian Dreadnought

Trample
When this creature enters, sacrifice it unless you sacrifice any number of creatures with total power 12 or greater.