Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Permission Denied

Counter target noncreature spell. Your opponents can't cast noncreature spells this turn.

Zinnia, Valley's Voice

Flying
Zinnia, Valley's Voice gets +X/+0, where X is the number of other creatures you control with base power 1.
Creature spells you cast have offspring {2}. (You may pay an additional {2} as you cast a creature spell. If you do, when that creature enters, create a 1/1 token copy of it.)

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Sol Ring

Perilous Landscape

{T}: Add {C}.
{T}, Sacrifice Perilous Landscape: Search your library for a basic Island, Mountain, or Plains card, put it onto the battlefield tapped, then shuffle.
Cycling {U}{R}{W} ({U}{R}{W}, Discard this card: Draw a card.)

Agate Instigator

Offspring {1}{R} (You may pay an additional {1}{R} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever another creature you control enters, this creature deals 1 damage to each opponent.

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Arcane Signet

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

Aven Shrine

Whenever a player casts a spell, that player gains X life, where X is the number of cards in all graveyards with the same name as that spell.

Render Silent

Counter target spell. Its controller can't cast spells this turn.

Hare Apparent

When this creature enters, create a number of 1/1 white Rabbit creature tokens equal to the number of other creatures you control named Hare Apparent.
A deck can have any number of cards named Hare Apparent.

Cloud Key

As Cloud Key enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Devilish Valet

Trample, haste
Alliance — Whenever another creature you control enters, double Devilish Valet's power until end of turn.

Silverquill Lecturer

Creature spells you cast have demonstrate. (Whenever you cast a creature spell, you may copy it. If you do, choose an opponent to also copy it. Each copy becomes a token.)

Witty Roastmaster

Alliance — Whenever another creature you control enters, Witty Roastmaster deals 1 damage to each opponent.

From the Rubble

As From the Rubble enters, choose a creature type.
At the beginning of your end step, return target creature card of the chosen type from your graveyard to the battlefield with a finality counter on it. (If a creature with a finality counter on it would die, exile it instead.)