Misleading Signpost

Flash
When this artifact enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)
{T}: Add {U}.

Plumeveil

Errant and Giada

Flash
Flying
You may look at the top card of your library any time.
You may cast spells with flash or flying from the top of your library.

Alms Collector

Flash
If an opponent would draw two or more cards, instead you and that player each draw a card.

Spell Queller

Flash
Flying
When this creature enters, exile target spell with mana value 4 or less.
When this creature leaves the battlefield, the exiled card's owner may cast that card without paying its mana cost.

Military Discipline

Flash
Enchant creature
When this Aura enters, enchanted creature gains first strike until end of turn.
Enchanted creature gets +1/+0.

Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Aboleth Spawn

Flash
Ward {2}
Probing Telepathy — Whenever a creature entering under an opponent's control causes a triggered ability of that creature to trigger, you may copy that ability. You may choose new targets for the copy.

Containment Priest

Flash
If a nontoken creature would enter and it wasn't cast, exile it instead.

Brineborn Cutthroat

Flash (You may cast this spell any time you could cast an instant.)
Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on this creature.

Deceiver Exarch

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, choose one —
• Untap target permanent you control.
• Tap target permanent an opponent controls.

Archivist of Oghma

Flash
Whenever an opponent searches their library, you gain 1 life and draw a card.

Portal Mage

Flash
When this creature enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)

Deep Gnome Terramancer

Flash
Mold Earth — Whenever one or more lands enter under an opponent's control without being played, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle. Do this only once each turn.

Asinine Antics

You may cast this spell as though it had flash if you pay {2} more to cast it.
For each creature your opponents control, create a Cursed Role token attached to that creature. (If you control another Role on it, put that one into the graveyard. Enchanted creature is 1/1.)