Putrid Goblin

Persist (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.)

Geothermal Bog

({T}: Add {B} or {R}.)
Geothermal Bog enters tapped.

Cast into the Fire

Choose one —
• Cast into the Fire deals 1 damage to each of up to two target creatures.
• Exile target artifact.

Skirk Prospector

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Cast Down

First Day of Class

Whenever a creature you control enters this turn, put a +1/+1 counter on it and it gains haste until end of turn.
Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Disintegrate

Disintegrate deals X damage to any target. If it's a creature, it can't be regenerated this turn, and if it would die this turn, exile it instead.

Ash Barrens

{T}: Add {C}.
Basic landcycling {1} ({1}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Goblin Matron

When Goblin Matron enters, you may search your library for a Goblin card, reveal that card, put it into your hand, then shuffle.

Swamp

Fireball

This spell costs {1} more to cast for each target beyond the first.
Fireball deals X damage divided evenly, rounded down, among any number of targets.

Goblin Grenade

As an additional cost to cast this spell, sacrifice a Goblin.
Goblin Grenade deals 5 damage to any target.

Bitter Reunion

When Bitter Reunion enters, you may discard a card. If you do, draw two cards.
{1}, Sacrifice Bitter Reunion: Creatures you control gain haste until end of turn.