Ovinomancer

When Ovinomancer enters, sacrifice it unless you return three basic lands you control to their owner's hand.
{T}, Return Ovinomancer to its owner's hand: Destroy target creature. It can't be regenerated. That creature's controller creates a 0/1 green Sheep creature token.

Supreme Exemplar

Flying
Champion an Elemental (When this enters, sacrifice it unless you exile another Elemental you control. When this leaves the battlefield, that card returns to the battlefield.)

Imperial Seal

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Cryptoplasm

At the beginning of your upkeep, you may have Cryptoplasm become a copy of another target creature, except it has this ability.

Avatar of Discord

({B/R} can be paid with either {B} or {R}.)
Flying
When Avatar of Discord enters, sacrifice it unless you discard two cards.

Discontinuity

During your turn, this spell costs {2}{U}{U} less to cast.
End the turn. (Exile all spells and abilities from the stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Phage the Untouchable

When Phage the Untouchable enters, if you didn't cast it from your hand, you lose the game.
Whenever Phage deals combat damage to a creature, destroy that creature. It can't be regenerated.
Whenever Phage deals combat damage to a player, that player loses the game.

Fabricate

Search your library for an artifact card, reveal it, put it into your hand, then shuffle.

Obeka, Brute Chronologist

{T}: The player whose turn it is may end the turn. (Exile all spells and abilities from the stack. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Boldwyr Heavyweights

Trample
When Boldwyr Heavyweights enters, each opponent may search their library for a creature card and put it onto the battlefield. Then each player who searched their library this way shuffles.

Hunted Dragon

Flying, haste
When Hunted Dragon enters, target opponent creates three 2/2 white Knight creature tokens with first strike.

Clackbridge Troll

Trample, haste
When Clackbridge Troll enters, target opponent creates three 0/1 white Goat creature tokens.
At the beginning of combat on your turn, any opponent may sacrifice a creature of their choice. If a player does, tap Clackbridge Troll, you gain 3 life, and you draw a card.

Sundial of the Infinite

{1}, {T}: End the turn. Activate only during your turn. (Exile all spells and abilities from the stack. Discard down to your maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Eater of Days

Flying, trample
When Eater of Days enters, you skip your next two turns.

Hunted Nightmare

Menace
When Hunted Nightmare enters, target opponent puts a deathtouch counter on a creature they control.

Endless Whispers

Each creature has "When this creature dies, choose target opponent. That player puts this card from its owner's graveyard onto the battlefield under their control at the beginning of the next end step."

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.)

Illusionary Mask

{X}: You may choose a creature card in your hand whose mana cost could be paid by some amount of, or all of, the mana you spent on {X}. If you do, you may cast that card face down as a 2/2 creature spell without paying its mana cost. If the creature that spell becomes as it resolves has not been turned face up and would assign or deal damage, be dealt damage, or become tapped, instead it's turned face up and assigns or deals damage, is dealt damage, or becomes tapped. Activate only as a sorcery.

Demonlord of Ashmouth

Flying
When Demonlord of Ashmouth enters, exile it unless you sacrifice another creature.
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Lord of Tresserhorn

When Lord of Tresserhorn enters, you lose 2 life, you sacrifice two creatures, and target opponent draws two cards.
{B}: Regenerate Lord of Tresserhorn.

Stifle

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

Chronozoa

Flying
Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Chronozoa dies, if it had no time counters on it, create two tokens that are copies of it.

Spitebellows

When Spitebellows leaves the battlefield, it deals 6 damage to target creature.
Evoke {1}{R}{R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Vexing Devil

When Vexing Devil enters, any opponent may have it deal 4 damage to them. If a player does, sacrifice Vexing Devil.

Sky Swallower

Flying
When Sky Swallower enters, target opponent gains control of all other permanents you control.

Wormfang Manta

Flying
When Wormfang Manta enters, you skip your next turn.
When Wormfang Manta leaves the battlefield, you take an extra turn after this one.

Hunted Horror

Trample
When Hunted Horror enters, target opponent creates two 3/3 green Centaur creature tokens with protection from black.

Leveler

When Leveler enters, exile all cards from your library.

Torpor Orb

Creatures entering don't cause abilities to trigger.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Hunted Phantasm

Hunted Phantasm can't be blocked.
When Hunted Phantasm enters, target opponent creates five 1/1 red Goblin creature tokens.

Diabolic Tutor

Treacherous Pit-Dweller

When Treacherous Pit-Dweller enters from a graveyard, target opponent gains control of it.
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Phyrexian Dreadnought

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

Nova Chaser

Trample
Champion an Elemental (When this enters, sacrifice it unless you exile another Elemental you control. When this leaves the battlefield, that card returns to the battlefield.)

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.