Ring of Valkas

Equipped creature has haste. (It can attack and {T} no matter when it came under your control.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's red.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Mountain

Krenko, Mob Boss

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

Forest

Chandra's Fury

Chandra's Fury deals 4 damage to target player or planeswalker and 1 damage to each creature that player or that planeswalker's controller controls.

Flinthoof Boar

This creature gets +1/+1 as long as you control a Mountain.
{R}: This creature gains haste until end of turn. (It can attack and {T} this turn.)

Arms Dealer

{1}{R}, Sacrifice a Goblin: This creature deals 4 damage to target creature.

Goblin Battle Jester

Whenever you cast a red spell, target creature can't block this turn.

Kindled Fury

Target creature gets +1/+0 and gains first strike until end of turn. (It deals combat damage before creatures without first strike.)

Dragon Hatchling

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

Cleaver Riot

Creatures you control gain double strike until end of turn. (They deal both first-strike and regular combat damage.)

Goblin Arsonist

When this creature dies, you may have it deal 1 damage to any target.

Krenko's Command

Create two 1/1 red Goblin creature tokens.

Torch Fiend

{R}, Sacrifice this creature: Destroy target artifact.

Titanic Growth

Target creature gets +4/+4 until end of turn.

Fire Elemental

Mogg Flunkies

This creature can't attack or block alone.

Furnace Whelp

Rummaging Goblin

Volcanic Geyser

Volcanic Geyser deals X damage to any target.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Trumpet Blast

Attacking creatures get +2/+0 until end of turn.

Bladetusk Boar

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Fervor

Creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Flames of the Firebrand

Flames of the Firebrand deals 3 damage divided as you choose among one, two, or three targets.

Serpent's Gift

Target creature gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Reckless Brute

Haste (This creature can attack and {T} as soon as it comes under your control.)
This creature attacks each combat if able.