Blind-Spot Giant

Blind-Spot Giant can't attack or block unless you control another Giant.

Basalt Ravager

When Basalt Ravager enters the battlefield, it deals X damage to any target, where X is the greatest number of creatures you control that have a creature type in common.

Bloodline Pretender

Changeling (This card is every creature type.)
As Bloodline Pretender enters the battlefield, choose a creature type.
Whenever another creature of the chosen type enters the battlefield under your control, put a +1/+1 counter on Bloodline Pretender.

Iron Myr

Thundercloud Shaman

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

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.

Stinkdrinker Daredevil

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

Mountain

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.

Barge In

Target attacking creature gets +2/+2 until end of turn. Each attacking non-Human creature gains trample until end of turn.

Thriving Bluff

Thriving Bluff enters the battlefield tapped.
As Thriving Bluff enters the battlefield, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Borderland Behemoth

Trample
Borderland Behemoth gets +4/+4 for each other Giant you control.

Squash

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

Ravenous Giant

At the beginning of your upkeep, Ravenous Giant deals 1 damage to you.

Goblin Motivator

{T}: Target creature gains haste until end of turn. (It can attack and {T} this turn.)