As Herald's Horn enters the battlefield, choose a creature type. Creature spells you cast of the chosen type cost {1} less to cast. At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Flying Whenever a player casts their second spell each turn, Ledger Shredder connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.) Tap four untapped Advisors you control: Target player mills twelve cards. A deck can have any number of cards named Persistent Petitioners.

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.) Tap four untapped Advisors you control: Target player mills twelve cards. A deck can have any number of cards named Persistent Petitioners.

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.) Tap four untapped Advisors you control: Target player mills twelve cards. A deck can have any number of cards named Persistent Petitioners.

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.) Tap four untapped Advisors you control: Target player mills twelve cards. A deck can have any number of cards named Persistent Petitioners.

Whenever an opponent casts a spell, you may reveal the top card of your library. If you do, counter that spell if it has the same mana value as the revealed card.

Creatures don't untap during their controllers' untap steps. Whenever a creature enters the battlefield, untap all creatures.

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Creature cards in graveyards and libraries can't enter the battlefield. Players can't cast spells from graveyards or libraries.

{T}: Target player exiles a card from their graveyard. {1}, Exile Relic of Progenitus: Exile all graveyards. Draw a card.

Cards in graveyards can't be the targets of spells or abilities. {4}, {T}: Exile Silent Gravestone and all cards from all graveyards. Draw a card.

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep. You draw a card at the beginning of the next turn's upkeep.

Draw three cards, then put two cards from your hand on top of your library in any order.

Counter target spell.

Draw two cards, then discard two cards. Untap up to three lands.

Counter target instant or sorcery spell. Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

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

Counter target noncreature spell unless its controller pays {2}.

Draw a card. If a graveyard has twenty or more cards in it, draw three cards instead.

Cleave {1}{U}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.) Counter target spell [that wasn't cast from its owner's hand].

{T}: Add {C}. Basic landcycling {1} ({1}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

As Cavern of Souls enters the battlefield, choose a creature type. {T}: Add {C}. {T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

{T}: Add {C}. {T}, Sacrifice Command Beacon: Put your commander into your hand from the command zone.

{T}: Add {C}. {2}, {T}: Each player draws a card, then discards a card.

Halimar Depths enters the battlefield tapped. When Halimar Depths enters the battlefield, look at the top three cards of your library, then put them back in any order. {T}: Add {U}.

{T}: Add {C}. {T}, Pay 1 life: Add {U}. {1}{U}, {T}, Sacrifice a Desert: Target player mills four cards.

({T}: Add {U}.)

{T}: Add {C}. {2}, {T}: Each player draws a card.

Mirrorpool enters the battlefield tapped. {T}: Add {C}. {2}{C}, {T}, Sacrifice Mirrorpool: Copy target instant or sorcery spell you control. You may choose new targets for the copy. {4}{C}, {T}, Sacrifice Mirrorpool: Create a token that's a copy of target creature you control.

({T}: Add {U}.) Mystic Sanctuary enters the battlefield tapped unless you control three or more other Islands. When Mystic Sanctuary enters the battlefield untapped, you may put target instant or sorcery card from your graveyard on top of your library.

{T}: Add {C}. {2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

{T}: Add {U}. Channel — {3}{U}, Discard Otawara, Soaring City: 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.

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

{T}: Add {C}. {2}, {T}, Sacrifice a Desert: Exile all graveyards.

Hideaway 4 (When this land enters the battlefield, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.) Shelldock Isle enters the battlefield tapped. {T}: Add {U}. {U}, {T}: You may play the exiled card without paying its mana cost if a library has twenty or fewer cards in it.

({T}: Add {U}.)

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Urza's Saga gains "{T}: Add {C}." II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'" III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

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

{T}: Add {C}. {1}, {T}, Sacrifice Mind Stone: Draw a card.

{T}: Add {C}{C}.

If an opponent searched their library this turn, you may pay {0} rather than pay this spell's mana cost. Target opponent mills thirteen cards.

Target player mills three cards. Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Each opponent mills fourteen cards. Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.) When you cycle Fractured Sanity, each opponent mills four cards.

Kicker {3}{U} Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

Whenever you draw a card, target opponent mills two cards. If two nonland cards that share a color were milled this way, repeat this process. {5}{U}: Draw a card, then discard a card.

Each opponent exiles cards from the top of their library until that player has exiled cards with total mana value 20 or more.

Target player mills two cards. Draw a card.

Search your library for an artifact card, reveal it, put it into your hand, then shuffle.

Choose target creature you control. Each other creature becomes a copy of that creature until end of turn, except it isn't legendary.

Look at the top three cards of your library, then put them back in any order. You may shuffle. Draw a card.

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Draw a card. Scry 2.

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.