Banish from Edoras

This spell costs {2} less to cast if it targets a tapped creature.
Exile target creature.

Inherited Envelope

When Inherited Envelope enters, the Ring tempts you.
{T}: Add one mana of any color.

Escape from Orthanc

Target creature gets +1/+3 and gains flying until end of turn. Untap it.

Erkenbrand, Lord of Westfold

Whenever Erkenbrand, Lord of Westfold or another Human you control enters, creatures you control get +1/+0 until end of 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.

Lotho, Corrupt Shirriff

Whenever a player casts their second spell each turn, you lose 1 life and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Errand-Rider of Gondor

When Errand-Rider of Gondor enters, draw a card. Then if you don't control a legendary creature, put a card from your hand on the bottom of your library.

Rally at the Hornburg

Create two 1/1 white Human Soldier creature tokens. Humans you control gain haste until end of turn.

Plains

Shadowfax, Lord of Horses

Horses you control have haste. (They can attack and {T} as soon as they come under your control.)
Whenever Shadowfax, Lord of Horses attacks, you may put a creature card with lesser power from your hand onto the battlefield tapped and attacking.

Great Hall of the Citadel

{T}: Add {C}.
{1}, {T}: Add two mana in any combination of colors. Spend this mana only to cast legendary spells.

Troll of Khazad-dûm

Troll of Khazad-dûm can't be blocked except by three or more creatures.
Swampcycling {1} ({1}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Sting, the Glinting Dagger

Equipped creature gets +1/+1 and has haste.
At the beginning of each combat, untap equipped creature.
Equipped creature has first strike as long as it's blocking or blocked by a Goblin or Orc.
Equip {2}

Swamp

Esquire of the King

{4}{W}, {T}: Creatures you control get +1/+1 until end of turn. This ability costs {2} less to activate if you control a legendary creature.

Dúnedain Blade

Equipped creature gets +2/+1.
Equip Human {1}
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Mountain

Bill the Pony

When Bill the Pony enters, create two Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Sacrifice a Food: Until end of turn, target creature you control assigns combat damage equal to its toughness rather than its power.

Oliphaunt

Trample
Whenever Oliphaunt attacks, another target creature you control gets +2/+0 and gains trample until end of turn.
Mountaincycling {1} ({1}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Rohirrim Lancer

Menace (This creature can't be blocked except by two or more creatures.)
When Rohirrim Lancer dies, the Ring tempts you.

Éowyn, Lady of Rohan

At the beginning of combat on your turn, target creature gains your choice of first strike or vigilance until end of turn. If that creature is equipped, it gains first strike and vigilance until end of turn instead.
Equip abilities you activate cost {1} less to activate.

Protector of Gondor

When Protector of Gondor enters, create a 1/1 white Human Soldier creature token.

Théoden, King of Rohan

Whenever Théoden, King of Rohan or another Human you control enters, target creature gains double strike until end of turn.

Morgul-Knife Wound

Enchant creature
Enchanted creature gets -3/-0 and has "At the beginning of your upkeep, exile this creature unless you pay 2 life."

Nasty End

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards. If the sacrificed creature was legendary, draw three cards instead.

Gimli's Fury

Target creature gets +3/+2 until end of turn. If it's legendary, it also gains trample until end of turn.