Earthshaker Giant

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

Firbolg Flutist

Enthralling Performance — When this creature enters, gain control of target creature you don't control until end of turn. Untap it. It gains haste and myriad until end of turn. (Whenever it attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

Borderland Behemoth

Trample
This creature gets +4/+4 for each other Giant you control.

Sunrise Sovereign

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

Callous Giant

If a source would deal 3 or less damage to this creature, prevent that damage.

Howling Giant

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

Inferno Titan

{R}: This creature gets +1/+0 until end of turn.
Whenever this creature enters or attacks, it deals 3 damage divided as you choose among one, two, or three targets.

Gilanra, Caller of Wirewood

{T}: Add {G}. When you spend this mana to cast a spell with mana value 6 or greater, draw a card.
Partner (You can have two commanders if both have partner.)

That's Mine

Create a Treasure token. (Then exile this card. You may cast the creature later from exile.)

Grabby Giant

Reach
{2}{R}, Sacrifice an artifact or land: Draw a card.

Grabby Giant // That's Mine

Dargo, the Shipwrecker

As an additional cost to cast this spell, you may sacrifice any number of artifacts and/or creatures. This spell costs {2} less to cast for each permanent sacrificed this way and {2} less to cast for each other artifact or creature you've sacrificed this turn.
Trample
Partner (You can have two commanders if both have partner.)

Craw Giant

Trample
Rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)

Bear Down

Destroy target artifact or enchantment. (Then exile this card. You may cast the creature later from exile.)

Stormkeld Vanguard

This creature can't be blocked by creatures with power 2 or less.

Stormkeld Vanguard // Bear Down

Valleymaker

{T}, Sacrifice a Mountain: This creature deals 3 damage to target creature.
{T}, Sacrifice a Forest: Choose a player. That player adds {G}{G}{G}.

Fertile Footsteps

Search your library for a basic land card, put it onto the battlefield, then shuffle. (Then exile this card. You may cast the creature later from exile.)

Beanstalk Giant

Beanstalk Giant's power and toughness are each equal to the number of lands you control.

Beanstalk Giant // Fertile Footsteps

Hamletback Goliath

Whenever another creature enters, you may put X +1/+1 counters on this creature, where X is that creature's power.

Thundercloud Shaman

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

Twice the Rage

Target creature gains double strike until end of turn. (Then exile this card. You may cast the creature later from exile.)