Stalwart Shield-Bearers

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

Vent Sentinel

Defender
{1}{R}, {T}: Vent Sentinel deals damage to target player or planeswalker equal to the number of creatures you control with defender.

Rolling Stones

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

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.

Wall of Blood

Defender (This creature can't attack.)
Pay 1 life: Wall of Blood gets +1/+1 until end of turn.

Blight Pile

Defender
{2}{B}, {T}: Each opponent loses X life, where X is the number of creatures with defender you control.

Wingmantle Chaplain

Defender
When Wingmantle Chaplain enters, create a 1/1 white Bird creature token with flying for each creature with defender you control.
Whenever another creature you control with defender enters, create a 1/1 white Bird creature token with flying.

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.

Kheru Bloodsucker

Whenever a creature you control with toughness 4 or greater dies, each opponent loses 2 life and you gain 2 life.
{2}{B}, Sacrifice another creature: Put a +1/+1 counter on Kheru Bloodsucker.

Alesha, Who Smiles at Death

First strike
Whenever Alesha, Who Smiles at Death attacks, you may pay {W/B}{W/B}. If you do, return target creature card with power 2 or less from your graveyard to the battlefield tapped and attacking.

Perimeter Captain

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