Aether Membrane

Defender; reach (This creature can block creatures with flying.)
Whenever Aether Membrane blocks a creature, return that creature to its owner's hand at end of combat.

Brimstone Trebuchet

Defender, reach
{T}: Brimstone Trebuchet deals 1 damage to each opponent.
Whenever a Knight enters the battlefield under your control, untap Brimstone Trebuchet.

Cathedral Membrane

({W/P} can be paid with either {W} or 2 life.)
Defender
When Cathedral Membrane dies during combat, it deals 6 damage to each creature it blocked this combat.

Fog Bank

Defender, flying
Prevent all combat damage that would be dealt to and dealt by Fog Bank.

Consulate Skygate

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

Coral Barrier

Defender (This creature can't attack.)
When Coral Barrier enters the battlefield, create a 1/1 blue Squid creature token with islandwalk. (It can't be blocked as long as defending player controls an Island.)

Hover Barrier

Jeskai Barricade

Flash (You may cast this spell any time you could cast an instant.)
Defender
When Jeskai Barricade enters the battlefield, you may return another target creature you control to its owner's hand.

Necropolis

Defender (This creature can't attack.)
Exile a creature card from your graveyard: Put X +0/+1 counters on Necropolis, where X is the exiled card's mana value.

Ageless Sentinels

Defender (This creature can't attack.)
Flying
When Ageless Sentinels blocks, it becomes a Bird Giant, and it loses defender. (It's no longer a Wall. This effect lasts indefinitely.)

Pramikon, Sky Rampart

Flying, defender
As Pramikon, Sky Rampart enters the battlefield, choose left or right.
Each player may attack only the nearest opponent in the chosen direction and planeswalkers controlled by that opponent.

Aetherflame Wall

Defender
Aetherflame Wall can block creatures with shadow as though they didn't have shadow.
{R}: Aetherflame Wall gets +1/+0 until end of turn.

Mnemonic Wall

Defender
When Mnemonic Wall enters the battlefield, you may return target instant or sorcery card from your graveyard to your hand.

Flowstone Wall

Defender (This creature can't attack.)
{R}: Flowstone Wall gets +1/-1 until end of turn.

Crude Rampart

Defender (This creature can't attack.)
Morph {4}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Crenellated Wall

Defender (This creature can't attack.)
{T}: Target creature gets +0/+4 until end of turn.

Crashing Drawbridge

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

Excavated Wall

Defender
{1}, {T}: Mill a card. (Put the top card of your library into your graveyard.)

Mirror Wall

Defender (This creature can't attack.)
{W}: Mirror Wall can attack this turn as though it didn't have defender.

Angelic Wall

Defender (This creature can't attack.)
Flying

Electrostatic Field

Defender
Whenever you cast an instant or sorcery spell, Electrostatic Field deals 1 damage to each opponent.

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.)

Illusionary Wall

Defender, flying, first strike
Cumulative upkeep {U} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Cinder Wall

Defender
When Cinder Wall blocks, destroy it at end of combat.

Coastal Bulwark

Defender
Coastal Bulwark gets +2/+0 as long as you control an Island.
{2}, {T}: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Blistering Barrier

Mistform Wall

Mistform Wall has defender as long as it's a Wall.
{1}: Mistform Wall becomes the creature type of your choice until end of turn.

Dark Maze

Defender (This creature can't attack.)
{0}: Dark Maze can attack this turn as though it didn't have defender. Exile it at the beginning of the next end step.

Mobile Fort

Defender (This creature can't attack.)
{3}: Mobile Fort gets +3/-1 until end of turn and can attack this turn as though it didn't have defender. Activate only once each turn.

Battle Rampart

Defender
{T}: Target creature gains haste until end of turn.

Glacial Wall

Academy Wall

Defender
Whenever you cast an instant or sorcery spell, you may draw a card. If you do, discard a card. This ability triggers only once each turn.

Amaranthine Wall

Defender
{2}: Amaranthine Wall gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Clockwork Drawbridge

Defender
{2}{W}, {T}: Tap target creature.

Living Wall

Defender (This creature can't attack.)
{1}: Regenerate Living Wall.

Dazzling Ramparts

Defender
{1}{W}, {T}: Tap target creature.

Alabaster Wall

Defender (This creature can't attack.)
{T}: Prevent the next 1 damage that would be dealt to any target this turn.

Nivix Barrier

Flash (You may cast this spell any time you could cast an instant.)
Defender (This creature can't attack.)
When Nivix Barrier enters the battlefield, target attacking creature gets -4/-0 until end of turn.

Fortified Rampart

Floodgate

Defender (This creature can't attack.)
When Floodgate has flying, sacrifice it.
When Floodgate leaves the battlefield, it deals damage equal to half the number of Islands you control, rounded down, to each nonblue creature without flying.