Guard Duty

Enchant creature
Enchanted creature has defender.

Hover Barrier

Wall of Essence

Defender (This creature can't attack.)
Whenever Wall of Essence is dealt combat damage, you gain that much life.

Wall of Shards

Defender, flying
Cumulative upkeep—An opponent gains 1 life. (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.)

Fortified Rampart

Glacial Wall

Angelic Wall

Defender (This creature can't attack.)
Flying

Vine Trellis

Defender (This creature can't attack.)
{T}: Add {G}.

Wall of Tanglecord

Defender
{G}: Wall of Tanglecord gains reach until end of turn. (It can block creatures with flying.)

Wall of Denial

Defender, flying
Shroud (This creature can't be the target of spells or abilities.)

Basilica Guards

Defender
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Axebane Guardian

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

Candletrap

Enchant creature
Enchanted creature has defender.
Prevent all combat damage that would be dealt by enchanted creature.
Coven — {2}{W}, Sacrifice Candletrap: Exile enchanted creature. Activate only if you control three or more creatures with different powers.

Wall of Glare

Defender (This creature can't attack.)
Wall of Glare can block any number of creatures.

Wall of Runes

Defender (This creature can't attack.)
When Wall of Runes enters the battlefield, scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Wall of Blossoms

Defender
When Wall of Blossoms enters the battlefield, draw a card.

Guardians of Meletis

Wall of Frost

Defender
Whenever Wall of Frost blocks a creature, that creature doesn't untap during its controller's next untap step.

Aurification

Whenever a creature deals damage to you, put a gold counter on it.
Each creature with a gold counter on it is a Wall in addition to its other creature types and has defender. (Those creatures can't attack.)
When Aurification leaves the battlefield, remove all gold counters from all creatures.

Dazzling Ramparts

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

Overgrown Battlement

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

Arcades, the Strategist

Flying, vigilance
Whenever a creature with defender enters the battlefield under your control, draw a card.
Each creature you control with defender assigns combat damage equal to its toughness rather than its power and can attack as though it didn't have defender.