Giantbaiting

Create a 4/4 red and green Giant Warrior creature token with haste. Exile it at the beginning of the next end step.
Conspire (As you cast this spell, you may tap two untapped creatures you control that share a color with it. When you do, copy it.)

Surtland Flinger

Whenever this creature attacks, you may sacrifice another creature. When you do, this creature deals damage equal to the sacrificed creature's power to any target. If the sacrificed creature was a Giant, this creature deals twice that much damage instead.

Cactus Preserve

This land enters tapped.
{T}: Add one mana of any type that a land you control could produce.
{3}: Until end of turn, this land becomes an X/X green Plant creature with reach, where X is the greatest mana value among your commanders. It's still a land.

Study Hall

{T}: Add {C}.
{1}, {T}: Add one mana of any color. When you spend this mana to cast your commander, scry X, where X is the number of times it's been cast from the command zone this game.

Elvish Handservant

Whenever a player casts a Giant spell, you may put a +1/+1 counter on this creature.

Joraga Invocation

Each creature you control gets +3/+3 until end of turn and must be blocked this turn if able.

Quakebringer

Your opponents can't gain life.
At the beginning of your upkeep, Quakebringer deals 2 damage to each opponent. This ability triggers only if Quakebringer is on the battlefield or if Quakebringer is in your graveyard and you control a Giant.
Foretell {2}{R}{R}

Earthshaker Giant

Trample
When this creature enters, other creatures you control get +3/+3 and gain trample until end of turn.

Pharagax Giant

Tribute 2 (As this creature enters, an opponent of your choice may put two +1/+1 counters on it.)
When this creature enters, if tribute wasn't paid, this creature deals 5 damage to each opponent.

Marshdrinker Giant

When this creature enters, destroy target Island or Swamp an opponent controls.

Squash

This spell costs {3} less to cast if you control a Giant.
Squash deals 6 damage to target creature or planeswalker.

Agatha of the Vile Cauldron

Activated abilities of creatures you control cost {X} less to activate, where X is Agatha's power. This effect can't reduce the mana in that cost to less than one mana.
{4}{R}{G}: Other creatures you control get +1/+1 and gain trample and haste until end of turn.

Ondu Giant

When this creature enters, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Arlinn, Embraced by the Moon

+1: Creatures you control get +1/+1 and gain trample until end of turn.
−1: Arlinn deals 3 damage to any target. Transform Arlinn.
−6: You get an emblem with "Creatures you control have haste and '{T}: This creature deals damage equal to its power to any target.'"

Arlinn Kord

+1: Until end of turn, up to one target creature gets +2/+2 and gains vigilance and haste.
0: Create a 2/2 green Wolf creature token. Transform Arlinn Kord.

Arlinn Kord // Arlinn, Embraced by the Moon

Tall as a Beanstalk

Enchant creature
Enchanted creature gets +3/+3, has reach, and is a Giant in addition to its other types.

Giant Inheritance

Enchant creature
Enchanted creature gets +5/+5 and has "Whenever this creature attacks, create a Monster Role token attached to up to one target attacking creature." (Enchanted creature gets +1/+1 and has trample.)
When this Aura is put into a graveyard from the battlefield, return it to its owner's hand.

Awaken the Ancient

Enchant Mountain
Enchanted Mountain is a 7/7 red Giant creature with haste. It's still a land.

Nylea's Colossus

Constellation — Whenever this creature or another enchantment you control enters, double target creature's power and toughness until end of turn.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Furystoke Giant

When this creature enters, other creatures you control gain "{T}: This creature deals 2 damage to any target" until end of turn.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Giant Trap Door Spider

{1}{R}{G}, {T}: Exile this creature and target creature without flying that's attacking you.

Tectonic Giant

Whenever this creature attacks or becomes the target of a spell an opponent controls, choose one —
• This creature deals 3 damage to each opponent.
• Exile the top two cards of your library. Choose one of them. Until the end of your next turn, you may play that card.

General Marhault Elsdragon

Whenever a creature you control becomes blocked, it gets +3/+3 until end of turn for each creature blocking it.

Howling Giant

Reach (This creature can block creatures with flying.)
When this creature enters, create two 2/2 green Wolf creature tokens.

Sanctum of Eternity

{T}: Add {C}.
{2}, {T}: Return target commander you own from the battlefield to your hand. Activate only during your turn.

Garruk Wildspeaker

+1: Untap two target lands.
−1: Create a 3/3 green Beast creature token.
−4: Creatures you control get +3/+3 and gain trample until end of turn.

Crush Underfoot

Choose a Giant creature you control. It deals damage equal to its power to target creature.

Dogpile

Dogpile deals damage to any target equal to the number of attacking creatures you control.

Faceless One

If Faceless One is your commander, choose a color before the game begins. Faceless One is the chosen color.
Choose a Background (You can have a Background as a second commander.)

Fire Giant's Fury

Target Giant you control gets +2/+2 and gains trample until end of turn. Whenever it deals combat damage to a player this turn, exile that many cards from the top of your library. Until the end of your next turn, you may play those cards.

Thundercloud Shaman

When this creature enters, it deals damage equal to the number of Giants you control to each non-Giant creature.

Witch's Clinic

{T}: Add {C}.
{2}, {T}: Target commander gains lifelink until end of turn.

Overwhelming Stampede

Until end of turn, creatures you control gain trample and get +X/+X, where X is the greatest power among creatures you control.

Giant Opportunity

You may sacrifice two Foods. If you do, create a 7/7 green Giant creature token. Otherwise, create three Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Raised by Giants

Commander creatures you own have base power and toughness 10/10 and are Giants in addition to their other types.

Dragon Throne of Tarkir

Equipped creature has defender and "{2}, {T}: Other creatures you control gain trample and get +X/+X until end of turn, where X is this creature's power."
Equip {3}

Stoneshock Giant

{6}{R}{R}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
When this creature becomes monstrous, creatures without flying your opponents control can't block this turn.

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

Stone Giant

{T}: Target creature you control with toughness less than this creature's power gains flying until end of turn. Destroy that creature at the beginning of the next end step.

Sunrise Sovereign

Other Giant creatures you control get +2/+2 and have trample.

Forge of Heroes

{T}: Add {C}.
{T}: Choose target commander that entered this turn. Put a +1/+1 counter on it if it's a creature and a loyalty counter on it if it's a planeswalker.

Giant Harbinger

When this creature enters, you may search your library for a Giant card, reveal it, then shuffle and put that card on top.

Giant's Ire

Giant's Ire deals 4 damage to target player or planeswalker. If you control a Giant, draw a card.

Opal Palace

{T}: Add {C}.
{1}, {T}: Add one mana of any color in your commander's color identity. If you spend this mana to cast your commander, it enters with a number of additional +1/+1 counters on it equal to the number of times it's been cast from the command zone this game.

Stinkdrinker Daredevil

Giant spells you cast cost {2} less to cast.

Command Beacon

{T}: Add {C}.
{T}, Sacrifice this land: Put your commander into your hand from the command zone.

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Calamity Bearer

If a Giant source you control would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Humbler of Mortals

Constellation — Whenever this creature or another enchantment you control enters, creatures you control gain trample until end of turn.