Pithing Needle

As this artifact enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.

Boromir, Warden of the Tower

Vigilance
Whenever an opponent casts a spell, if no mana was spent to cast it, counter that spell.
Sacrifice Boromir: Creatures you control gain indestructible until end of turn. The Ring tempts you.

Fateful Absence

Destroy target creature or planeswalker. Its controller investigates. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Mountain

Battlefield Forge

{T}: Add {C}.
{T}: Add {R} or {W}. This land deals 1 damage to you.

Mentor of the Meek

Whenever another creature you control with power 2 or less enters, you may pay {1}. If you do, draw a card.

Clifftop Retreat

This land enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.

Sundering Growth

Destroy target artifact or enchantment, then populate. (Create a token that's a copy of a creature token you control.)

Norin the Wary

When a player casts a spell or a creature attacks, exile Norin. Return it to the battlefield under its owner's control at the beginning of the next end step.

Thalia, Guardian of Thraben

First strike
Noncreature spells cost {1} more to cast.

Saradoc, Master of Buckland

Whenever Saradoc or another nontoken creature you control with power 2 or less enters, create a 1/1 white Halfling creature token.
Tap two other untapped Halflings you control: Saradoc gets +2/+0 and gains lifelink until end of turn.

Skyknight Squire

Whenever another creature you control enters, put a +1/+1 counter on this creature.
As long as this creature has three or more +1/+1 counters on it, it has flying and is a Knight in addition to its other types.

Plains

Defense Grid

Each spell costs {3} more to cast except during its controller's turn.

Remorseful Cleric

Flying
Sacrifice this creature: Exile target player's graveyard.

Adeline, Resplendent Cathar

Vigilance
Adeline's power is equal to the number of creatures you control.
Whenever you attack, for each opponent, create a 1/1 white Human creature token that's tapped and attacking that player or a planeswalker they control.

Thran Portal

This land enters tapped unless you control two or fewer other lands.
As this land enters, choose a basic land type.
This land is the chosen type in addition to its other types.
Mana abilities of this land cost an additional 1 life to activate.

Thalia's Lieutenant

When this creature enters, put a +1/+1 counter on each other Human you control.
Whenever another Human you control enters, put a +1/+1 counter on this creature.

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Settle the Wreckage

Exile all attacking creatures target player controls. That player may search their library for that many basic land cards, put those cards onto the battlefield tapped, then shuffle.

Chain Lightning

Chain Lightning deals 3 damage to any target. Then that player or that permanent's controller may pay {R}{R}. If the player does, they may copy this spell and may choose a new target for that copy.

Moonrage Brute

First strike
Ward—Pay 3 life.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Brutal Cathar

Whenever this creature enters or transforms into Brutal Cathar, exile target creature an opponent controls until this creature leaves the battlefield.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)