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.

Flamewright

{1}, {T}: Create a 1/1 colorless Construct artifact creature token with defender.
{T}, Sacrifice a creature with defender: Flamewright deals 1 damage to any target.

Overgrown Battlement

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

Wall of Omens

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

Glory of Warfare

As long as it's your turn, creatures you control get +2/+0.
As long as it's not your turn, creatures you control get +0/+2.

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.

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Ludevic, Necro-Alchemist

At the beginning of each player's end step, that player may draw a card if a player other than you lost life this turn.
Partner (You can have two commanders if both have partner.)

Stalwart Shield-Bearers

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

High Alert

Each creature you control assigns combat damage equal to its toughness rather than its power.
Creatures you control can attack as though they didn't have defender.
{2}{W}{U}: Untap target creature.

Brave the Sands

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

Perimeter Captain

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

Axebane Guardian

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

Crashing Drawbridge

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

Sidar Kondo of Jamuraa

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
Creatures your opponents control without flying or reach can't block creatures with power 2 or less.
Partner (You can have two commanders if both have partner.)

Atla Palani, Nest Tender

{2}, {T}: Create a 0/1 green Egg creature token with defender.
Whenever an Egg you control dies, reveal cards from the top of your library until you reveal a creature card. Put that card onto the battlefield and the rest on the bottom of your library in a random order.

Tower Defense

Creatures you control get +0/+5 and gain reach until end of turn.

Slaughter the Strong

Each player chooses any number of creatures they control with total power 4 or less, then sacrifices all other creatures they control.

Teyo, the Shieldmage

You have hexproof. (You can't be the target of spells or abilities your opponents control.)
−2: Create a 0/3 white Wall creature token with defender.

Wall of Denial

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