Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

Subterranean Scout

When Subterranean Scout enters, target creature with power 2 or less can't be blocked this turn.

Rush the Room

Target creature gets +1/+0 and gains first strike until end of turn. If it's a Goblin or Orc, it also gains haste until end of turn.

Spark Spray

Spark Spray deals 1 damage to any target.
Cycling {R} ({R}, Discard this card: Draw a card.)

Goblin Fireleaper

{1}{R}: Goblin Fireleaper gets +1/+0 until end of turn.
When Goblin Fireleaper dies, it deals damage equal to its power to target creature an opponent controls.

Mogg War Marshal

Echo {1}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Mogg War Marshal enters or dies, create a 1/1 red Goblin creature token.

Ferocity of the Wilds

Attacking non-Human creatures you control get +1/+0 and have trample.

Book of Mazarbul

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Amass Orcs 1. (Put a +1/+1 counter on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)
II — Amass Orcs 2.
III — Creatures you control get +1/+0 and gain menace until end of turn.

Slaying Fire

Slaying Fire deals 3 damage to any target.
Adamant — If at least three red mana was spent to cast this spell, it deals 4 damage instead.

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.

Battle-Scarred Goblin

Whenever Battle-Scarred Goblin becomes blocked, it deals 1 damage to each creature blocking it.

Mountain

Foray of Orcs

Amass Orcs 2. When you do, Foray of Orcs deals X damage to target creature an opponent controls, where X is the amassed Army's power. (To amass Orcs 2, put two +1/+1 counters on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)

Grishnákh, Brash Instigator

When Grishnákh, Brash Instigator enters, amass Orcs 2. When you do, until end of turn, gain control of target nonlegendary creature an opponent controls with power less than or equal to the amassed Army's power. Untap that creature. It gains haste until end of turn.

Skirk Prospector

Goblin Medics

Whenever Goblin Medics becomes tapped, it deals 1 damage to any target.

Swarming of Moria

Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Amass Orcs 2. (Put two +1/+1 counters on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)

Empty the Warrens

Create two 1/1 red Goblin creature tokens.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)