Grim Contest

Choose target creature you control and target creature an opponent controls. Each of those creatures deals damage equal to its toughness to the other.

Have

Galvanic Alchemist

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Galvanic Alchemist is paired with another creature, each of those creatures has "{2}{U}: Untap this creature."

Suspicious Bookcase

Defender
{3}, {T}: Target creature can't be blocked this turn.

Crashing Drawbridge

Defender
{T}: Creatures you control gain haste until end of turn.

Consulate Skygate

Defender
Reach (This creature can block creatures with flying.)

Overgrown Battlement

Defender
{T}: Add {G} for each creature you control with defender.

Ulvenwald Abomination

Ulvenwald Captive

Defender
{T}: Add {G}.
{5}{G}{G}: Transform Ulvenwald Captive.

Ulvenwald Captive // Ulvenwald Abomination

Wall of Roots

Defender
Put a -0/-1 counter on Wall of Roots: Add {G}. Activate only once each turn.

Coral Colony

Defender
{1}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender. (To mill a card, a player puts the top card of their library into their graveyard.)

Walking Bulwark

Defender
{2}: Until end of turn, target creature with defender gains haste, can attack as though it didn't have defender, and assigns combat damage equal to its toughness rather than its power. Activate only as a sorcery.

Dramatic Reversal

Untap all nonland permanents you control.

Doorkeeper

Defender
{2}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender.

Assault Formation

Each creature you control assigns combat damage equal to its toughness rather than its power.
{G}: Target creature with defender can attack this turn as though it didn't have defender.
{2}{G}: Creatures you control get +0/+1 until end of turn.

Forest

Axebane Guardian

Defender
{T}: Add X mana in any combination of colors, where X is the number of creatures you control with defender.

Steel Wall

Island

Shield-Wall Sentinel

Defender
When Shield-Wall Sentinel enters, you may search your library for a creature card with defender, reveal it, put it into your hand, then shuffle.