Hydroelectric Laboratory

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}.

Hydroelectric Specimen

Flash
When this creature enters, you may change the target of target instant or sorcery spell with a single target to this creature.

Hydroelectric Specimen // Hydroelectric Laboratory

Breakthrough

Draw four cards, then choose X cards in your hand and discard the rest.

Exclude

Counter target creature spell.
Draw a card.

Island

Diamond Mare

As this creature enters, choose a color.
Whenever you cast a spell of the chosen color, you gain 1 life.

Archway of Innovation

This land enters tapped unless you control an Island.
{T}: Add {U}.
{U}, {T}: The next spell you cast this turn has improvise. (Your artifacts can help cast that spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Leyline of Transformation

If this card is in your opening hand, you may begin the game with it on the battlefield.
As this enchantment enters, choose a creature type.
Creatures you control are the chosen type in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard this card: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Bill the Pony

When Bill the Pony enters, create two Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Sacrifice a Food: Until end of turn, target creature you control assigns combat damage equal to its toughness rather than its power.

Counterspell

Soporific Springs

Sink into Stupor

Return target spell or nonland permanent an opponent controls to its owner's hand.

Sink into Stupor // Soporific Springs

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Gnostro, Voice of the Crags

{T}: Choose one. X is the number of spells you've cast this turn.
• Scry X.
• Gnostro deals X damage to target creature.
• You gain X life.

Champion's Victory

Cast this spell only during the declare attackers step and only if you've been attacked this step.
Return target attacking creature to its owner's hand.

Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, untap another target creature you control.

Sensei's Divining Top

{1}: Look at the top three cards of your library, then put them back in any order.
{T}: Draw a card, then put this artifact on top of its owner's library.

Aragorn, the Uniter

Whenever you cast a white spell, create a 1/1 white Human Soldier creature token.
Whenever you cast a blue spell, scry 2.
Whenever you cast a red spell, Aragorn deals 3 damage to target opponent.
Whenever you cast a green spell, target creature gets +4/+4 until end of turn.

Rivendell

Rivendell enters tapped unless you control a legendary creature.
{T}: Add {U}.
{1}{U}, {T}: Scry 2. Activate only if you control a legendary creature.

Forest

Minamo, School at Water's Edge

{T}: Add {U}.
{U}, {T}: Untap target legendary permanent.

Command Tower

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

Adeline, Resplendent Cathar

Vigilance
Adeline's power is equal to the number of creatures you control.
Whenever you attack, for each opponent, create a 1/1 white Human creature token that's tapped and attacking that player or a planeswalker they control.

Firestorm

As an additional cost to cast this spell, discard X cards.
Firestorm deals X damage to each of X targets.

Benalish Marshal

Bloodline Pretender

Changeling (This card is every creature type.)
As this creature enters, choose a creature type.
Whenever another creature you control of the chosen type enters, put a +1/+1 counter on this creature.

Aetherize

Return all attacking creatures to their owner's hand.

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Gilded Ghoda

Whenever this creature attacks while saddled, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Negate

Ahn-Crop Champion

You may exert this creature as it attacks. When you do, untap all other creatures you control. (An exerted creature won't untap during your next untap step.)

Blessed Reversal

You gain 3 life for each creature attacking you.

Armored Warhorse

Guardian Sunmare

Ward {2}
Whenever this creature attacks while saddled, search your library for a nonland permanent card with mana value 3 or less, put it onto the battlefield, then shuffle.
Saddle 4

Academy Ruins

{T}: Add {C}.
{1}{U}, {T}: Put target artifact card from your graveyard on top of your library.

Neck Breaker

Attacking creatures you control get +1/+0 and have trample.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform this creature.

Breakneck Rider

At the beginning of each upkeep, if no spells were cast last turn, transform this creature.

Breakneck Rider // Neck Breaker

Castle Vantress

This land enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Adaptive Automaton

As this creature enters, choose a creature type.
This creature is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Crested Sunmare

Other Horses you control have indestructible.
At the beginning of each end step, if you gained life this turn, create a 5/5 white Horse creature token.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Clockwork Steed

This creature enters with four +1/+0 counters on it.
This creature can't be blocked by artifact creatures.
At end of combat, if this creature attacked or blocked this combat, remove a +1/+0 counter from it.
{X}, {T}: Put up to X +1/+0 counters on this creature. This ability can't cause the total number of +1/+0 counters on this creature to be greater than four. Activate only during your upkeep.

Broken Dam

Tap one or two target creatures without horsemanship.

Terrain Generator

{T}: Add {C}.
{2}, {T}: You may put a basic land card from your hand onto the battlefield tapped.

Phantom Steed

Flash
When this creature enters, exile another target creature you control until this creature leaves the battlefield.
Whenever this creature attacks, create a tapped and attacking token that's a copy of the exiled card, except it's an Illusion in addition to its other types. Sacrifice that token at end of combat.

Get Out

Choose one —
• Counter target creature or enchantment spell.
• Return one or two target creatures and/or enchantments you own to your hand.

Surge Mare

This creature can't be blocked by green creatures.
Whenever this creature deals damage to an opponent, you may draw a card. If you do, discard a card.
{1}{U}: This creature gets +2/-2 until end of turn.

Leyline of Anticipation

If this card is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.

Seat of the Synod

Gylwain, Casting Director

Whenever Gylwain or another nontoken creature you control enters, choose one —
• Create a Royal Role token attached to that creature.
• Create a Sorcerer Role token attached to that creature.
• Create a Monster Role token attached to that creature.

Sidar Kondo of Jamuraa

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
Creatures your opponents control without flying or reach can't block creatures with power 2 or less.
Partner (You can have two commanders if both have partner.)