Error

Trial

Return all creatures blocking or blocked by target creature to their owner's hand.

Trial // Error

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

Pillar of the Paruns

{T}: Add one mana of any color. Spend this mana only to cast a multicolored spell.

Azorius Herald

Azorius Herald can't be blocked.
When Azorius Herald enters, you gain 4 life.
When Azorius Herald enters, sacrifice it unless {U} was spent to cast it.

Leyline of Singularity

If Leyline of Singularity is in your opening hand, you may begin the game with it on the battlefield.
All nonland permanents are legendary.

Walking Archive

Defender (This creature can't attack.)
Walking Archive enters with a +1/+1 counter on it.
At the beginning of each player's upkeep, that player draws a card for each +1/+1 counter on Walking Archive.
{2}{W}{U}: Put a +1/+1 counter on Walking Archive.

Celestial Ancient

Flying
Whenever you cast an enchantment spell, put a +1/+1 counter on each creature you control.

Court Hussar

Vigilance
When Court Hussar enters, look at the top three cards of your library, then put one of them into your hand and the rest on the bottom of your library in any order.
When Court Hussar enters, sacrifice it unless {W} was spent to cast it.

Convolute

Counter target spell unless its controller pays {4}.

Paladin of Prahv

Whenever Paladin of Prahv deals damage, you gain that much life.
Forecast — {1}{W}, Reveal Paladin of Prahv from your hand: Whenever target creature deals damage this turn, you gain that much life. (Activate only during your upkeep and only once each turn.)

Faith's Fetters

Enchant permanent
When Faith's Fetters enters, you gain 4 life.
Enchanted permanent can't attack or block, and its activated abilities can't be activated unless they're mana abilities.

Aethermage's Touch

Reveal the top four cards of your library. You may put a creature card from among them onto the battlefield. It gains "At the beginning of your end step, return this creature to its owner's hand." Then put the rest of the cards revealed this way on the bottom of your library in any order.

Dovescape

({W/U} can be paid with either {W} or {U}.)
Whenever a player casts a noncreature spell, counter that spell. That player creates X 1/1 white and blue Bird creature tokens with flying, where X is the spell's mana value.

Plumes of Peace

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.
Forecast — {W}{U}, Reveal Plumes of Peace from your hand: Tap target creature. (Activate only during your upkeep and only once each turn.)

Ocular Halo

Enchant creature
Enchanted creature has "{T}: Draw a card."
{W}: Enchanted creature gains vigilance until end of turn.

Swift Silence

Counter all other spells. Draw a card for each spell countered this way.

Overrule

Counter target spell unless its controller pays {X}. You gain X life.

Skyscribing

Each player draws X cards.
Forecast — {2}{U}, Reveal Skyscribing from your hand: Each player draws a card. (Activate only during your upkeep and only once each turn.)

Droning Bureaucrats

{X}, {T}: Each creature with mana value X can't attack or block this turn.

Island

Azorius Chancery

Azorius Chancery enters tapped.
When Azorius Chancery enters, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Minister of Impediments

({W/U} can be paid with either {W} or {U}.)
{T}: Tap target creature.

Suppression Field

Activated abilities cost {2} more to activate unless they're mana abilities.

Azorius Guildmage

{2}{W}: Tap target creature.
{2}{U}: Counter target activated ability. (Mana abilities can't be targeted.)

Soulsworn Jury

Defender (This creature can't attack.)
{1}{U}, Sacrifice Soulsworn Jury: Counter target creature spell.

Prahv, Spires of Order

{T}: Add {C}.
{4}{W}{U}, {T}: Prevent all damage a source of your choice would deal this turn.

Pride of the Clouds

Flying
Pride of the Clouds gets +1/+1 for each other creature on the battlefield with flying.
Forecast — {2}{W}{U}, Reveal Pride of the Clouds from your hand: Create a 1/1 white and blue Bird creature token with flying. (Activate only during your upkeep and only once each turn.)

Isperia the Inscrutable

Flying
Whenever Isperia the Inscrutable deals combat damage to a player, choose a card name. That player reveals their hand. If a card with the chosen name is revealed this way, search your library for a creature card with flying, reveal it, put it into your hand, then shuffle.

Azorius Signet

Proclamation of Rebirth

Return up to three target creature cards with mana value 1 or less from your graveyard to the battlefield.
Forecast — {5}{W}, Reveal Proclamation of Rebirth from your hand: Return target creature card with mana value 1 or less from your graveyard to the battlefield. (Activate only during your upkeep and only once each turn.)

Azorius Aethermage

Whenever a permanent is returned to your hand, you may pay {1}. If you do, draw a card.

Grand Arbiter Augustin IV

White spells you cast cost {1} less to cast.
Blue spells you cast cost {1} less to cast.
Spells your opponents cast cost {1} more to cast.

Azorius Ploy

Prevent all combat damage target creature would deal this turn.
Prevent all combat damage that would be dealt to target creature this turn.

Demand

Search your library for a multicolored card, reveal it, put it into your hand, then shuffle.

Supply

Create X 1/1 green Saproling creature tokens.

Supply // Demand

Plains

Writ of Passage

Enchant creature
Whenever enchanted creature attacks, if its power is 2 or less, it can't be blocked this turn.
Forecast — {1}{U}, Reveal Writ of Passage from your hand: Target creature with power 2 or less can't be blocked this turn. (Activate only during your upkeep and only once each turn.)