Battle of Hoover Dam

As Battle of Hoover Dam enters, choose NCR or Legion.
• NCR — At the beginning of your end step, return target creature card with mana value 3 or less from your graveyard to the battlefield with a finality counter on it.
• Legion — Whenever a creature you control dies, put two +1/+1 counters on target creature you control.

Firemane Commando

Flying
Whenever you attack with two or more creatures, draw a card.
Whenever another player attacks with two or more creatures, they draw a card if none of those creatures attacked you.

Sigarda's Vanguard

Flash
Flying
Whenever Sigarda's Vanguard enters or attacks, choose any number of creatures with different powers. Those creatures gain double strike until end of turn.

Niko, Light of Hope

When Niko, Light of Hope enters, create two Shard tokens. (They're enchantments with "{2}, Sacrifice this enchantment: Scry 1, then draw a card.")
{2}, {T}: Exile target nonlegendary creature you control. Shards you control become copies of it until the beginning of the next end step. Return it to the battlefield under its owner's control at the beginning of the next end step.

Bishop of Binding

When Bishop of Binding enters, exile target creature an opponent controls until Bishop of Binding leaves the battlefield.
Whenever Bishop of Binding attacks, target Vampire gets +X/+X until end of turn, where X is the power of the exiled card.

Storm Fleet Negotiator

Flying
Parley — Whenever Storm Fleet Negotiator attacks, each player reveals the top card of their library. For each nonland card revealed this way, you create a Map token. Then each player draws a card. (A Map token is an artifact with "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

Sungold Sentinel

Whenever Sungold Sentinel enters or attacks, exile up to one target card from a graveyard.
Coven — {1}{W}: Choose a color. Sungold Sentinel gains hexproof from that color until end of turn and can't be blocked by creatures of that color this turn. Activate only if you control three or more creatures with different powers.

Galepowder Mage

Flying
Whenever Galepowder Mage attacks, exile another target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Cemetery Illuminator

Flying
Whenever Cemetery Illuminator enters or attacks, exile a card from a graveyard.
You may look at the top card of your library any time.
Once each turn, you may cast a spell from the top of your library if it shares a card type with a card exiled with Cemetery Illuminator.

Protean Thaumaturge

Constellation — Whenever an enchantment you control enters, you may have Protean Thaumaturge become a copy of another target creature, except it has this ability.

Estrid's Invocation

You may have Estrid's Invocation enter as a copy of an enchantment you control, except it has "At the beginning of your upkeep, you may exile this enchantment. If you do, return it to the battlefield under its owner's control."

Shadow Puppeteers

Flying, ward {2}
When Shadow Puppeteers enters, create two 1/1 black Faerie Rogue creature tokens with flying.
Whenever a creature you control with flying attacks, you may have it become a red Dragon with base power and toughness 4/4 in addition to its other colors and types until end of turn.

Overlord of the Mistmoors

Impending 4—{2}{W}{W} (If you cast this spell for its impending cost, it enters with four time counters and isn't a creature until the last is removed. At the beginning of your end step, remove a time counter from it.)
Whenever Overlord of the Mistmoors enters or attacks, create two 2/1 white Insect creature tokens with flying.

All-Seeing Arbiter

Flying
Whenever All-Seeing Arbiter enters or attacks, draw two cards, then discard a card.
Whenever you discard a card, target creature an opponent controls gets -X/-0 until your next turn, where X is the number of different mana values among cards in your graveyard.

Redemption Choir

Lifelink
Coven — Whenever Redemption Choir enters or attacks, if you control three or more creatures with different powers, return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Overlord of the Floodpits

Impending 4—{1}{U}{U} (If you cast this spell for its impending cost, it enters with four time counters and isn't a creature until the last is removed. At the beginning of your end step, remove a time counter from it.)
Flying
Whenever Overlord of the Floodpits enters or attacks, draw two cards, then discard a card.

Titan of Littjara

As Titan of Littjara enters, choose a creature type.
Titan of Littjara is the chosen type in addition to its other types.
Whenever Titan of Littjara enters or attacks, you may draw a card for each other creature you control that shares a creature type with it. If you do, discard a card.

The Myriad Pools

(Transforms from The Everflowing Well.)
{T}: Add {U}.
Whenever you cast a permanent spell using mana produced by The Myriad Pools, up to one other target permanent you control becomes a copy of that spell until end of turn.

The Everflowing Well

When The Everflowing Well enters, mill two cards, then draw two cards.
Descend 8 — At the beginning of your upkeep, if there are eight or more permanent cards in your graveyard, transform The Everflowing Well.

The Everflowing Well // The Myriad Pools

Weathered Sentinels

Defender, vigilance, reach, trample
Weathered Sentinels can attack players who attacked you during their last turn as though it didn't have defender.
Whenever Weathered Sentinels attacks, it gets +3/+3 and gains indestructible until end of turn.

Norn's Choirmaster

Flying, first strike
Whenever a commander you control enters or attacks, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Ethereal Valkyrie

Flying
Whenever Ethereal Valkyrie enters or attacks, draw a card, then exile a card from your hand face down. It becomes foretold. Its foretell cost is its mana cost reduced by {2}. (On a later turn, you may cast it for its foretell cost, even if this creature has left the battlefield.)

Ethereal Forager

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Flying
Whenever Ethereal Forager attacks, you may return an instant or sorcery card exiled with Ethereal Forager to its owner's hand.

Silverwing Squadron

Flying, vigilance
Silverwing Squadron's power and toughness are each equal to the number of creatures you control.
Whenever Silverwing Squadron attacks, create a number of 2/2 white Knight creature tokens with vigilance equal to the number of opponents you have.

Court of Vantress

When Court of Vantress enters, you become the monarch.
At the beginning of your upkeep, choose up to one other target enchantment or artifact. If you're the monarch, you may create a token that's a copy of it. If you're not the monarch, you may have Court of Vantress become a copy of it, except it has this ability.

Mirrormade

You may have Mirrormade enter as a copy of any artifact or enchantment on the battlefield.

Ox Drover

Vigilance
Ox Drover can't be blocked by Oxen.
Whenever Ox Drover enters or attacks, target opponent creates a 2/4 white Ox creature token and you draw a card.

Fractured Identity

Exile target nonland permanent. Each player other than its controller creates a token that's a copy of it.

Ondu Spiritdancer

Whenever an enchantment you control enters, you may create a token that's a copy of it. Do this only once each turn.

Leonin Warleader

Whenever Leonin Warleader attacks, create two 1/1 white Cat creature tokens with lifelink that are tapped and attacking.

Giggling Skitterspike

Indestructible
Whenever Giggling Skitterspike attacks, blocks, or becomes the target of a spell, it deals damage equal to its power to each opponent.
{5}: Monstrosity 5. (If this creature isn't monstrous, put five +1/+1 counters on it and it becomes monstrous.)

Clever Impersonator

You may have Clever Impersonator enter as a copy of any nonland permanent on the battlefield.

Senator Peacock

Artifacts you control are Clues in addition to their other types and have "{2}, Sacrifice this artifact: Draw a card."
Whenever you sacrifice a Clue, target creature can't be blocked this turn.

Extravagant Replication

At the beginning of your upkeep, create a token that's a copy of another target nonland permanent you control.

Jacked Rabbit

Ravenous (This creature enters with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Whenever Jacked Rabbit attacks, create a number of 1/1 white Rabbit creature tokens equal to Jacked Rabbit's power.

Replication Technique

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it. Players may choose new targets for their copies.)
Create a token that's a copy of target permanent you control.

Sakashima's Protege

Flash
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
You may have Sakashima's Protege enter as a copy of any permanent that entered this turn.

Niko Aris

When Niko Aris enters, create X Shard tokens. (They're enchantments with "{2}, Sacrifice this enchantment: Scry 1, then draw a card.")
+1: Up to one target creature you control can't be blocked this turn. Whenever that creature deals damage this turn, return it to its owner's hand.
−1: Niko Aris deals 2 damage to target tapped creature for each card you've drawn this turn.
−1: Create a Shard token.

Guardian Scalelord

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following abilities until end of turn.)
Flying
Whenever this creature attacks, return target nonland permanent card with mana value X or less from your graveyard to the battlefield, where X is this creature's power.

Dream Trawler

Flying, lifelink
Whenever you draw a card, Dream Trawler gets +1/+0 until end of turn.
Whenever Dream Trawler attacks, draw a card.
Discard a card: Dream Trawler gains hexproof until end of turn. Tap it.

Colossal Whale

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Colossal Whale attacks, you may exile target creature defending player controls until Colossal Whale leaves the battlefield. (That creature returns under its owner's control.)

The Flood of Mars

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Water Always Wins — Whenever The Flood of Mars attacks, put a flood counter on another target creature or land. If it's a creature, it becomes a copy of The Flood of Mars. If it's a land, it becomes an Island in addition to its other types.

Identity Thief

Whenever Identity Thief attacks, you may exile another target nontoken creature. If you do, Identity Thief becomes a copy of that creature until end of turn. Return the exiled card to the battlefield under its owner's control at the beginning of the next end step.

Sun Titan

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

Coveted Falcon

Flying
Whenever Coveted Falcon attacks, gain control of target permanent you own but don't control.
Disguise {1}{U}
When Coveted Falcon is turned face up, target opponent gains control of any number of target permanents you control. Draw a card for each one they gained control of this way.

Thalakos Deceiver

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Thalakos Deceiver attacks and isn't blocked, you may sacrifice it. If you do, gain control of target creature. (This effect lasts indefinitely.)

Mirage Mirror

{2}: Mirage Mirror becomes a copy of target artifact, creature, enchantment, or land until end of turn.

Twenty-Toed Toad

Your maximum hand size is twenty.
Whenever you attack with two or more creatures, put a +1/+1 counter on Twenty-Toed Toad and draw a card.
Whenever Twenty-Toed Toad attacks, you win the game if there are twenty or more counters on it or you have twenty or more cards in 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 or attacks, tap target permanent. It doesn't untap during its controller's next untap step.

Sludge Monster

Whenever Sludge Monster enters or attacks, put a slime counter on up to one other target creature.
Non-Horror creatures with slime counters on them lose all abilities and have base power and toughness 2/2.

Warkite Marauder

Flying
Whenever Warkite Marauder attacks, target creature defending player controls loses all abilities and has base power and toughness 0/1 until end of turn.

Skystrike Officer

Flying
Whenever Skystrike Officer attacks, create a 1/1 colorless Soldier artifact creature token.
Tap three untapped Soldiers you control: Draw a card.

Bishop of Rebirth

Vigilance
Whenever Bishop of Rebirth attacks, you may return target creature card with mana value 3 or less from your graveyard to the battlefield.

Azure Beastbinder

Vigilance
Azure Beastbinder can't be blocked by creatures with power 2 or greater.
Whenever Azure Beastbinder attacks, up to one target artifact, creature, or planeswalker an opponent controls loses all abilities until your next turn. If it's a creature, it also has base power and toughness 2/2 until your next turn.