Hellrider

Haste
Whenever a creature you control attacks, Hellrider deals 1 damage to the player or planeswalker it's attacking.

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Slagstone Refinery

Whenever Slagstone Refinery or another nontoken artifact you control is put into a graveyard from the battlefield or is put into exile from the battlefield, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Radiant Performer

Flash
When Radiant Performer enters, if you cast it from your hand, choose target spell or ability that targets only a single permanent or player. Copy that spell or ability for each other permanent or player the spell or ability could target. Each copy targets a different one of those permanents and players.

Scalding Salamander

Whenever Scalding Salamander attacks, you may have it deal 1 damage to each creature without flying defending player controls.

Powerstone Minefield

Whenever a creature attacks or blocks, Powerstone Minefield deals 2 damage to it.

Circle of Flame

Whenever a creature without flying attacks you or a planeswalker you control, Circle of Flame deals 1 damage to that creature.

Lightmine Field

Whenever one or more creatures attack, Lightmine Field deals damage to each of those creatures equal to the number of attacking creatures.

Sneak Attack

{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step.

Sol Ring

Dire-Strain Anarchist

Menace, haste
Whenever Dire-Strain Anarchist attacks, it deals 2 damage to each of up to one target creature, up to one target player, and/or up to one target planeswalker.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Volatile Arsonist

Menace, haste
Whenever Volatile Arsonist attacks, it deals 1 damage to each of up to one target creature, up to one target player, and/or up to one target planeswalker.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Volatile Arsonist // Dire-Strain Anarchist

Captain Rex Nebula

At the beginning of combat on your turn, choose target nonland permanent you control. Until end of turn, it becomes a Vehicle artifact with base power and toughness each equal to its mana value, and it gains crew 2 and "Crash Land — Whenever this Vehicle deals damage, roll a six-sided die. If the result is equal to this Vehicle's mana value, sacrifice this Vehicle, then it deals that much damage to any target."

Boros Signet

Devil K. Nevil

Haste
When Devil K. Nevil enters, jump it over any number of creatures. If it clears those creatures, put that many +1/+1 counters on it. (You can see a jumping demonstration at DevilKNevil.com.)

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. Talisman of Conviction deals 1 damage to you.

Ghirapur Aether Grid

Tap two untapped artifacts you control: Ghirapur Aether Grid deals 1 damage to any target.

Goblin Blastronauts

When Goblin Blastronauts enters, open an Attraction.
Whenever you roll a 6, you may copy the spell, ability, or Attraction visit that caused you to roll that die. You may choose new targets for the copy.

Rings of Brighthearth

Whenever you activate an ability, if it isn't a mana ability, you may pay {2}. If you do, copy that ability. You may choose new targets for the copy.

Arcane Signet

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

Complaints Clerk

When Complaints Clerk enters, open an Attraction. (Put the top card of your Attraction deck onto the battlefield.)
Whenever you roll a 1, create a 1/1 white Clown Robot artifact creature token.