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}."

Take to the Streets

Creatures you control get +2/+2 until end of turn. Citizens you control get an additional +1/+1 and gain vigilance until end of turn.

Angelic Observer

This spell costs {1} less to cast for each Citizen you control.
Flying

Hold for Ransom

Enchant creature
Enchanted creature can't attack or block and has "{7}: Hold for Ransom's controller sacrifices it and draws a card. Activate only as a sorcery."

Ceremonial Groundbreaker

Equipped creature gets +2/+1 and has trample.
Equip Citizen {1}
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Gathering Throng

When Gathering Throng enters, you may search your library for any number of cards named Gathering Throng, reveal them, put them into your hand, then shuffle.

Plains

Civil Servant

Whenever Civil Servant attacks, you may tap another untapped Citizen you control. If you do, Civil Servant gets +1/+0 and gains lifelink until end of turn.

Ballroom Brawlers

Whenever Ballroom Brawlers attacks, Ballroom Brawlers and up to one other target creature you control both gain your choice of first strike or lifelink until end of turn.

Civic Gardener

Whenever Civic Gardener attacks, untap target creature or land.

Prizefight

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)
Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Elegant Entourage

Alliance — Whenever another creature you control enters, target creature other than Elegant Entourage gets +1/+1 and gains trample until end of turn.

Freelance Muscle

Whenever Freelance Muscle attacks or blocks, it gets +X/+X until end of turn, where X is the greatest power and/or toughness among other creatures you control.

Forest

Darling of the Masses

Other Citizens you control get +1/+0.
Whenever Darling of the Masses attacks, create a 1/1 green and white Citizen creature token.

Celebrity Fencer

Alliance — Whenever another creature you control enters, put a +1/+1 counter on Celebrity Fencer.

Botanical Plaza

Botanical Plaza enters tapped.
{T}: Add {G} or {W}.
{2}{G}{W}, {T}, Sacrifice Botanical Plaza: Draw a card.

Cabaretti Courtyard

When Cabaretti Courtyard enters, sacrifice it. When you do, search your library for a basic Mountain, Forest, or Plains card, put it onto the battlefield tapped, then shuffle and you gain 1 life.