Inti, Seneschal of the Sun

Whenever you attack, you may discard a card. When you do, put a +1/+1 counter on target attacking creature. It gains trample until end of turn.
Whenever you discard one or more cards, exile the top card of your library. You may play that card until your next end step.

Shadow of the Goblin

Unreliable Visions — At the beginning of your first main phase, discard a card. If you do, draw a card.
Undying Vengeance — Whenever you play a land or cast a spell from anywhere other than your hand, this enchantment deals 1 damage to each opponent.

Sear

Sear deals 4 damage to target creature or planeswalker.

Tersa Lightshatter

Haste
When Tersa Lightshatter enters, discard up to two cards, then draw that many cards.
Whenever Tersa Lightshatter attacks, if there are seven or more cards in your graveyard, exile a card at random from your graveyard. You may play that card this turn.

Marauding Mako

Whenever you discard one or more cards, put that many +1/+1 counters on this creature.
Cycling {2} ({2}, Discard this card: Draw a card.)

Hobgoblin, Mantled Marauder

Flying, haste
Whenever you discard a card, Hobgoblin gets +2/+0 until end of turn.

Count on Luck

At the beginning of your upkeep, exile the top card of your library. You may play that card this turn.

Masked Meower

Haste
Discard a card, Sacrifice this creature: Draw a card.

Thunder Magic

Tiered (Choose one additional cost.)
• Thunder — {0} — Thunder Magic deals 2 damage to target creature.
• Thundara — {3} — Thunder Magic deals 4 damage to target creature.
• Thundaga — {5}{R} — Thunder Magic deals 8 damage to target creature.