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

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.

{T}: Add {U}. {2}{U}: Put an hour counter on Midnight Clock. At the beginning of each upkeep, put an hour counter on Midnight Clock. When the twelfth hour counter is put on Midnight Clock, shuffle your hand and graveyard into your library, then draw seven cards. Exile Midnight Clock.

Sky Diamond enters the battlefield tapped. {T}: Add {U}.

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

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)

Flying As an additional cost to cast blue permanent spells, you may pay 2 life. Those spells cost {U} less to cast if you paid life this way. This effect reduces only the amount of blue mana you pay. Whenever you cast a blue permanent spell, draw a card.

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Whenever another snow permanent enters the battlefield under your control, you may have target player mill two cards.

{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 Terisian Mindbreaker attacks, defending player mills half their library, rounded up. Unearth {1}{U}{U}{U} ({1}{U}{U}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Whenever you cast a blue spell, target player mills two cards.

Enchant player At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn.

Whenever you draw a card, you may have target player mill a card.

Whenever Marit Lage's Slumber or another snow permanent enters the battlefield under your control, scry 1. At the beginning of your upkeep, if you control ten or more snow permanents, sacrifice Marit Lage's Slumber. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

Counter target spell. Its controller mills three cards.

Untap all nonland permanents you control.

Counter target spell. Its controller mills three cards.

Dark Depths enters the battlefield with ten ice counters on it. {3}: Remove an ice counter from Dark Depths. When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

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

Myriad Landscape enters the battlefield tapped. {T}: Add {C}. {2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

({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.

Path of Ancestry enters the battlefield tapped. {T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

You have no maximum hand size. {T}: Add {C}.

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.

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.) Target player mills half their library, rounded down.

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.

Draw a card for each Human you control.