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.

Grond, the Gatebreaker

Trample
As long as it's your turn and you control an Army, Grond, the Gatebreaker is an artifact creature.
Crew 3 (Tap any number of creatures you control with total power 3 or more: This Vehicle becomes an artifact creature until end of turn.)

Barad-dûr

Barad-dûr enters tapped unless you control a legendary creature.
{T}: Add {B}.
{X}{X}{B}, {T}: Amass Orcs X. Activate only if a creature died this turn.

Gothmog, Morgul Lieutenant

When Gothmog, Morgul Lieutenant enters, 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.)
Creature tokens you control have deathtouch.

Warbeast of Gorgoroth

Whenever Warbeast of Gorgoroth or another creature you control with power 4 or greater dies, 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.)

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

March from the Black Gate

When March from the Black Gate enters and whenever an Army you control attacks, 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.)

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.

Gorbag of Minas Morgul

Whenever a Goblin or Orc you control deals combat damage to a player, you may sacrifice it. When you do, choose one —
• Draw a card.
• Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Gríma Wormtongue

Your opponents can't gain life.
{T}, Sacrifice another creature: Target player loses 1 life. If the sacrificed creature was legendary, amass Orcs 2.

Foreboding Ruins

As Foreboding Ruins enters, you may reveal a Swamp or Mountain card from your hand. If you don't, Foreboding Ruins enters tapped.
{T}: Add {B} or {R}.

Orcish Medicine

Target creature gains your choice of lifelink or indestructible until end of turn.
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.)

Easterling Vanguard

When Easterling Vanguard dies, 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.)

Mordor Trebuchet

Defender
Whenever you attack with one or more Goblins and/or Orcs, create a 2/1 colorless Construct artifact creature token with flying named Ballistic Boulder that's tapped and attacking. Sacrifice that token at end of combat.

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.)

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.)

The Torment of Gollum

Target opponent reveals their hand. You choose a nonland card from it. That player discards that card.
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.)

Mordor Muster

You draw a card and you lose 1 life.
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.)

Mountain

Shagrat, Loot Bearer

Whenever Shagrat, Loot Bearer attacks, attach up to one target Equipment to it. Then amass Orcs X, where X is the number of Equipment attached to Shagrat. (Control of the Equipment doesn't change. To amass Orcs X, put X +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.)

Mauhúr, Uruk-hai Captain

Menace
If one or more +1/+1 counters would be put on an Army, Goblin, or Orc you control, that many plus one +1/+1 counters are put on it instead.

Assault on Osgiliath

Amass Orcs X, then Goblins and Orcs you control gain double strike and haste until end of turn. (To amass Orcs X, put X +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.)

Mirkwood Bats

Flying
Whenever you create or sacrifice a token, each opponent loses 1 life.

Swamp

Dunland Crebain

Flying
When Dunland Crebain enters, 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.)

Uglúk of the White Hand

Whenever another creature you control dies, put a +1/+1 counter on Uglúk of the White Hand. If that creature was a Goblin or Orc, put two +1/+1 counters on Uglúk instead.