Agatha's Soul Cauldron

You may spend mana as though it were mana of any color to activate abilities of creatures you control.
Creatures you control with +1/+1 counters on them have all activated abilities of all creature cards exiled with Agatha's Soul Cauldron.
{T}: Exile target card from a graveyard. When a creature card is exiled this way, put a +1/+1 counter on target creature you control.

Amonkhet Raceway

Start your engines! (If you have no speed, it starts at 1. It increases once on each of your turns when an opponent loses life. Max speed is 4.)
{T}: Add {C}.
Max speed — {T}: Target creature gains haste until end of turn.

Draconautics Engineer

Exhaust — {R}: Other creatures you control gain haste until end of turn. Put a +1/+1 counter on this creature. (Activate each exhaust ability only once.)
Exhaust — {3}{R}: Create a 4/4 red Dinosaur Dragon creature token with flying.

Three Tree City

As Three Tree City enters, choose a creature type.
{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to the number of creatures you control of the chosen type.

Rundvelt Hordemaster

Other Goblins you control get +1/+1.
Whenever this creature or another Goblin you control dies, exile the top card of your library. If it's a Goblin creature card, you may cast that card until the end of your next turn.

Howlsquad Heavy

Start your engines!
Other Goblins you control have haste.
At the beginning of combat on your turn, create a 1/1 red Goblin creature token. That token attacks this combat if able.
Max speed — {T}: Add {R} for each Goblin you control.

Burnout Bashtronaut

Menace
Start your engines! (If you have no speed, it starts at 1. It increases once on each of your turns when an opponent loses life. Max speed is 4.)
{2}: This creature gets +1/+0 until end of turn.
Max speed — This creature has double strike.

Mountain

Fanatical Firebrand

Haste (This creature can attack and {T} as soon as it comes under your control.)
{T}, Sacrifice this creature: It deals 1 damage to any target.

Searslicer Goblin

Raid — At the beginning of your end step, if you attacked this turn, create a 1/1 red Goblin creature token.

Greasewrench Goblin

Exhaust — {2}{R}: Discard up to two cards, then draw that many cards. Put a +1/+1 counter on this creature. (Activate each exhaust ability only once.)

Burst Lightning

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Burst Lightning deals 2 damage to any target. If this spell was kicked, it deals 4 damage instead.

Krenko, Mob Boss

{T}: Create X 1/1 red Goblin creature tokens, where X is the number of Goblins you control.