Take Up the Shield

Put a +1/+1 counter on target creature. It gains lifelink and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Woolly Razorback

Woolly Razorback enters with three ice counters on it.
As long as Woolly Razorback has an ice counter on it, prevent all combat damage it would deal and it has defender.
Whenever Woolly Razorback blocks, remove an ice counter from it.

Weathered Sentinels

Defender, vigilance, reach, trample
Weathered Sentinels can attack players who attacked you during their last turn as though it didn't have defender.
Whenever Weathered Sentinels attacks, it gets +3/+3 and gains indestructible until end of turn.

Hold the Line

Blocking creatures get +7/+7 until end of turn.

Dragon Throne of Tarkir

Equipped creature has defender and "{2}, {T}: Other creatures you control gain trample and get +X/+X until end of turn, where X is this creature's power."
Equip {3}

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.

Barrow-Blade

Equipped creature gets +1/+1.
Whenever equipped creature blocks or becomes blocked by a creature, that creature loses all abilities until end of turn.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Loyal Sentry

When Loyal Sentry blocks a creature, destroy that creature and Loyal Sentry.

Vanguard's Shield

Equipped creature gets +0/+3 and can block an additional creature each combat.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Rammas Echor, Ancient Shield

Whenever you cast your second spell each turn, draw a card, then create a 0/3 white Wall creature token with defender.
At the beginning of combat on your turn, creatures you control with defender gain exalted until end of turn. (Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each instance of exalted among permanents you control.)

Smite

Stalwart Shield-Bearers

Defender
Other creatures you control with defender get +0/+2.

Angelic Wall

Defender (This creature can't attack.)
Flying

Jeskai Barricade

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

Wall of Hope

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

Royal Trooper

Whenever Royal Trooper blocks, it gets +2/+2 until end of turn.

Noble Stand

Whenever a creature you control blocks, you gain 2 life.

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Perimeter Captain

Defender
Whenever a creature you control with defender blocks, you may gain 2 life.

Curtain of Light

Cast this spell only during combat after blockers are declared.
Target unblocked attacking creature becomes blocked. (This spell works on creatures that can't be blocked.)
Draw a card.

Mirror Shield

Equipped creature gets +0/+2 and has hexproof and "Whenever a creature with deathtouch blocks or becomes blocked by this creature, destroy that creature."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Battle Cry

Untap all white creatures you control.
Whenever a creature blocks this turn, it gets +0/+1 until end of turn.

Wall of Glare

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

Wall of Nets

Defender (This creature can't attack.)
At end of combat, exile all creatures blocked by Wall of Nets.
When Wall of Nets leaves the battlefield, return all cards exiled with Wall of Nets to the battlefield under their owners' control.

Make a Stand

Creatures you control get +1/+0 and gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Righteousness

Target blocking creature gets +7/+7 until end of turn.

High Ground

Each creature you control can block an additional creature each combat.

Give No Ground

Target creature gets +2/+6 until end of turn and can block any number of creatures this turn.

Serene Master

Whenever Serene Master blocks, exchange its power and the power of target creature it's blocking until end of combat.

Masako the Humorless

Flash
Tapped creatures you control can block as though they were untapped.

Amaranthine Wall

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

Alaborn Zealot

When Alaborn Zealot blocks a creature, destroy that creature and Alaborn Zealot.

Flumph

Defender, flying
Whenever Flumph is dealt damage, you and target opponent each draw a card.

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.

Fortified Rampart

Wall of Essence

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

Basilisk Collar

Equipped creature has deathtouch and lifelink.
Equip {2}

Ashes of the Abhorrent

Players can't cast spells from graveyards or activate abilities of cards in graveyards.
Whenever a creature dies, you gain 1 life.

Sinstriker's Will

Enchant creature
Enchanted creature has "{T}: This creature deals damage equal to its power to target attacking or blocking creature."

Rolling Stones

Wall creatures can attack as though they didn't have defender.

Escarpment Fortress

Defender (This creature can't attack.)
Reach (This creature can block creatures with flying.)
Other creatures you control get +1/+0.
Whenever you attack with two or more creatures, draw a card.

Echo Circlet

Equipped creature can block an additional creature each combat.
Equip {1}

Guardian of the Gateless

Flying
Guardian of the Gateless can block any number of creatures.
Whenever Guardian of the Gateless blocks, it gets +1/+1 until end of turn for each creature it's blocking.

Entangler

Enchant creature
Enchanted creature can block any number of creatures.

Manor Gargoyle

Defender
Manor Gargoyle has indestructible as long as it has defender.
{1}: Until end of turn, Manor Gargoyle loses defender and gains flying.

Pride Guardian

Defender
Whenever Pride Guardian blocks, you gain 3 life.

Dingus Staff

Whenever a creature dies, Dingus Staff deals 2 damage to that creature's controller.

Wall of Omens

Defender
When Wall of Omens enters, draw a card.

Caduceus, Staff of Hermes

Equipped creature has lifelink.
As long as you have 30 or more life, equipped creature gets +5/+5 and has indestructible and "Prevent all damage that would be dealt to this creature."
Equip {W}{W}

Plains

Sting, the Glinting Dagger

Equipped creature gets +1/+1 and has haste.
At the beginning of each combat, untap equipped creature.
Equipped creature has first strike as long as it's blocking or blocked by a Goblin or Orc.
Equip {2}

Watchdog

Watchdog blocks each combat if able.
As long as Watchdog is untapped, all creatures attacking you get -1/-0.

Goldenglow Moth

Flying
Whenever Goldenglow Moth blocks, you may gain 4 life.

Valor Made Real

Target creature can block any number of creatures this turn.

Bastion Protector

Commander creatures you control get +2/+2 and have indestructible.

Palace Guard

Palace Guard can block any number of creatures.

Proper Burial

Whenever a creature you control dies, you gain life equal to that creature's toughness.

Moonlit Wake

Whenever a creature dies, you gain 1 life.

Brave the Sands

Creatures you control have vigilance.
Each creature you control can block an additional creature each combat.

Gallantry

Target blocking creature gets +4/+4 until end of turn.
Draw a card.

Blacksmith's Skill

Target permanent gains hexproof and indestructible until end of turn. If it's an artifact creature, it gets +2/+2 until end of turn.

Magnetic Web

If a creature with a magnet counter on it attacks, all creatures with magnet counters on them attack if able.
Whenever a creature with a magnet counter on it attacks, all creatures with magnet counters on them block that creature this turn if able.
{1}, {T}: Put a magnet counter on target creature.

Defensive Formation

Rather than the attacking player, you assign the combat damage of each creature attacking you. You can divide that creature's combat damage as you choose among any of the creatures blocking it.

Wakestone Gargoyle

Defender, flying
{1}{W}: Creatures you control with defender can attack this turn as though they didn't have defender.

Rally

Blocking creatures get +1/+1 until end of turn.

Wall of Reverence

Defender, flying
At the beginning of your end step, you may gain life equal to the power of target creature you control.

Act of Heroism

Untap target creature. It gets +2/+2 until end of turn and can block an additional creature this turn.

Peregrine Mask

Equipped creature has defender, flying, and first strike.
Equip {2}

Luminous Wake

Enchant creature
Whenever enchanted creature attacks or blocks, you gain 4 life.

Jareth, Leonine Titan

Whenever Jareth, Leonine Titan blocks, it gets +7/+7 until end of turn.
{W}: Jareth gains protection from the color of your choice until end of turn.