Mage's Attendant

When Mage's Attendant enters, create a 1/1 blue Wizard creature token with "{1}, Sacrifice this creature: Counter target noncreature spell unless its controller pays {1}."

Plains

Harper Recruiter

Flying
Whenever Harper Recruiter attacks, look at the top four cards of your library. You may reveal a Cleric card, a Rogue card, a Warrior card, and/or a Wizard card from among them and put those cards into your hand. Put the rest on the bottom of your library in a random order.

Anointed Peacekeeper

Vigilance
As Anointed Peacekeeper enters, look at an opponent's hand, then choose any card name.
Spells your opponents cast with the chosen name cost {2} more to cast.
Activated abilities of sources with the chosen name cost {2} more to activate unless they're mana abilities.

Archpriest of Iona

Archpriest of Iona's power is equal to the number of creatures in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)
At the beginning of combat on your turn, if you have a full party, target creature gets +1/+1 and gains flying until end of turn.

Seasoned Hallowblade

Discard a card: Tap Seasoned Hallowblade. It gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Mutavault

{T}: Add {C}.
{1}: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Squad Commander

When Squad Commander enters, create a 1/1 white Kor Warrior creature token for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)
At the beginning of combat on your turn, if you have a full party, creatures you control get +1/+0 and gain indestructible until end of turn.

Journey to Oblivion

This spell costs {1} less to cast for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)
When Journey to Oblivion enters, exile target nonland permanent an opponent controls until Journey to Oblivion leaves the battlefield.

Raffine's Informant

When Raffine's Informant enters, it connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

Citadel Gate

Citadel Gate enters tapped.
As Citadel Gate enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Extraction Specialist

Lifelink
When Extraction Specialist enters, return target creature card with mana value 2 or less from your graveyard to the battlefield. That creature can't attack or block for as long as you control Extraction Specialist.

Practiced Tactics

Choose target attacking or blocking creature. Practiced Tactics deals damage to that creature equal to twice the number of creatures in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Kayla's Reconstruction

Look at the top seven cards of your library. Put up to X artifact and/or creature cards with mana value 3 or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

Luminarch Aspirant

At the beginning of combat on your turn, put a +1/+1 counter on target creature you control.