Goblin King

Other Goblins get +1/+1 and have mountainwalk.

Professional Face-Breaker

Treasure

Menace
Whenever one or more creatures you control deal combat damage to a player, create a Treasure token.
Sacrifice a Treasure: Exile the top card of your library. You may play that card this turn.

Rankle, Master of Pranks

Flying, haste
Whenever Rankle deals combat damage to a player, choose any number —
• Each player discards a card.
• Each player loses 1 life and draws a card.
• Each player sacrifices a creature of their choice.

Soul Warden

Whenever another creature enters, you gain 1 life.

Shivan Dragon

Sarkhan, Wanderer to Shiv

Flying
{R}: This creature gets +1/+0 until end of turn.

Elves of Deep Shadow

{T}: Add {B}. This creature deals 1 damage to you.

Good-Fortune Unicorn

Whenever another creature you control enters, put a +1/+1 counter on that creature.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature of their choice.

Fecundity

Whenever a creature dies, that creature's controller may draw a card.

Mayhem Devil

Whenever a player sacrifices a permanent, this creature deals 1 damage to any target.

Moldervine Reclamation

Whenever a creature you control dies, you gain 1 life and draw a card.

Kobolds of Kher Keep

Prossh, Skyraider of Kher

When you cast this spell, create X 0/1 red Kobold creature tokens named Kobolds of Kher Keep, where X is the amount of mana spent to cast it.
Flying
Sacrifice another creature: Prossh gets +1/+0 until end of turn.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Sphinx of the Second Sun

Flying
At the beginning of each of your postcombat main phases, there is an additional beginning phase after this phase. (The beginning phase includes the untap, upkeep, and draw steps.)

Secret Lair Drop