Glimpse the Cosmos

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.
As long as you control a Giant, you may cast Glimpse the Cosmos from your graveyard by paying {U} rather than paying its mana cost. If you cast Glimpse the Cosmos this way and it would be put into your graveyard, exile it instead.

Kroxa and Kunoros

Vigilance, menace, lifelink
Whenever Kroxa and Kunoros enters the battlefield or attacks, you may exile five cards from your graveyard. When you do, return target creature card from your graveyard to the battlefield.

Inescapable Brute

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Inescapable Brute must be blocked if able.

Invasion of the Giants

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Scry 2.
II — Draw a card. Then you may reveal a Giant card from your hand. When you do, Invasion of the Giants deals 2 damage to target opponent or planeswalker.
III — The next Giant spell you cast this turn costs {2} less to cast.

Wandering Graybeard

Kinship — At the beginning of your upkeep, you may look at the top card of your library. If it shares a creature type with Wandering Graybeard, you may reveal it. If you do, you gain 4 life.

Borderland Behemoth

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

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}

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.

Stinkdrinker Daredevil

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

Aegar, the Freezing Flame

Whenever a creature or planeswalker an opponent controls is dealt excess damage, if a Giant, Wizard, or spell you controlled dealt damage to it this turn, draw a card.

Sun Titan

Vigilance
Whenever Sun Titan enters the battlefield or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Bearer of the Heavens

When Bearer of the Heavens dies, destroy all permanents at the beginning of the next end step.

Hamletback Goliath

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

Hall of Storm Giants

If you control two or more other lands, Hall of Storm Giants enters the battlefield tapped.
{T}: Add {U}.
{5}{U}: Until end of turn, Hall of Storm Giants becomes a 7/7 blue Giant creature with ward {3}. It's still a land. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)

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.

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.

Battle of Frost and Fire

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Battle of Frost and Fire deals 4 damage to each non-Giant creature and each planeswalker.
II — Scry 3.
III — Whenever you cast a spell with mana value 5 or greater this turn, draw two cards, then discard a card.

Outland Colossus

Renown 6 (When this creature deals combat damage to a player, if it isn't renowned, put six +1/+1 counters on it and it becomes renowned.)
Outland Colossus can't be blocked by more than one creature.

Cyclone Summoner

When Cyclone Summoner enters the battlefield, if you cast it from your hand, return all permanents to their owners' hands except for Giants, Wizards, and lands.

Furystoke Giant

When Furystoke Giant enters the battlefield, 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.)

Brion Stoutarm

Lifelink
{R}, {T}, Sacrifice another creature: Brion Stoutarm deals damage equal to the sacrificed creature's power to target player or planeswalker.

Surtland Flinger

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

Undermountain Adventurer

Vigilance
When Undermountain Adventurer enters the battlefield, you take the initiative.
{T}: Add {G}{G}. If you've completed a dungeon, add six {G} instead.

Thundercloud Shaman

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

Sludge Titan

Trample
Whenever Sludge Titan enters the battlefield or attacks, mill five cards. You may put a creature card and/or a land card from among them into your hand.

Frost Titan

Whenever Frost Titan becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}.
Whenever Frost Titan enters the battlefield or attacks, tap target permanent. It doesn't untap during its controller's next untap step.

Ancient Amphitheater

As Ancient Amphitheater enters the battlefield, you may reveal a Giant card from your hand. If you don't, Ancient Amphitheater enters the battlefield tapped.
{T}: Add {R} or {W}.

Earthshaker Giant

Trample
When Earthshaker Giant enters the battlefield, other creatures you control get +3/+3 and gain trample until end of turn.

Giant Harbinger

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

Firbolg Flutist

Enthralling Performance — When Firbolg Flutist enters the battlefield, 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 that's a copy of that creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

Crush Underfoot

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

Cast Off

Destroy all non-Giant creatures. (Then exile this card. You may cast the creature later from exile.)

Realm-Cloaked Giant

Realm-Cloaked Giant // Cast Off

Oathsworn Giant

Vigilance
Other creatures you control get +0/+2 and have vigilance.

Elvish Handservant

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

Arbor Colossus

Reach
{3}{G}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
When Arbor Colossus becomes monstrous, destroy target creature with flying an opponent controls.

Kalemne's Captain

Vigilance
{5}{W}{W}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
When Kalemne's Captain becomes monstrous, exile all artifacts and enchantments.

Thryx, the Sudden Storm

Flash
Flying
Spells you cast with mana value 5 or greater cost {1} less to cast and can't be countered.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters the battlefield, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Sunrise Sovereign

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

Bear Down

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

Stormkeld Vanguard

Stormkeld Vanguard can't be blocked by creatures with power 2 or less.

Stormkeld Vanguard // Bear Down

Grave Titan

Deathtouch
Whenever Grave Titan enters the battlefield or attacks, create two 2/2 black Zombie creature tokens.

Arbiter of Knollridge

Vigilance
When Arbiter of Knollridge enters the battlefield, each player's life total becomes the highest life total among all players.

Hundred-Handed One

Vigilance
{3}{W}{W}{W}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
As long as Hundred-Handed One is monstrous, it has reach and can block an additional ninety-nine creatures each combat.

Feudkiller's Verdict

You gain 10 life. Then if you have more life than an opponent, create a 5/5 white Giant Warrior creature token.

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 Stoneshock Giant becomes monstrous, creatures without flying your opponents control can't block this turn.

Blight Titan

Deathtouch
Whenever Blight Titan enters the battlefield or attacks, mill two cards, then incubate X, where X is the number of creature cards in your graveyard. (Create an Incubator token with X +1/+1 counters on it and "{2}: Transform this artifact." It transforms into a 0/0 Phyrexian artifact creature.)