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

Elvish Handservant

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

Crystalline Giant

At the beginning of combat on your turn, choose a kind of counter at random that this creature doesn't have on it from among flying, first strike, deathtouch, hexproof, lifelink, menace, reach, trample, vigilance, and +1/+1. Put a counter of that kind on this creature.

Durkwood Tracker

{1}{G}, {T}: If this creature is on the battlefield, it deals damage equal to its power to target attacking creature. That creature deals damage equal to its power to this creature.

Tall as a Beanstalk

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

Wilson, Refined Grizzly

This spell can't be countered.
Vigilance, reach, trample
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Choose a Background (You can have a Background as a second commander.)

Elfsworn Giant

Reach (This creature can block creatures with flying.)
Landfall — Whenever a land you control enters, create a 1/1 green Elf Warrior creature token.

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.)

Raised by Giants

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

Hamlet Glutton

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
This spell costs {2} less to cast if it's bargained.
Trample
When this creature enters, you gain 3 life.

Howling Giant

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

Earthshaker Giant

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