Wall of Runes

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

Sky Tether

Enchant creature
Enchanted creature has defender and loses flying.

Arcades, the Strategist

Flying, vigilance
Whenever a creature you control with defender enters, 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.

Bamboo Grove Archer

Defender, reach
Channel — {4}{G}, Discard Bamboo Grove Archer: Destroy target creature with flying.

Forest

Brokers Ascendancy

At the beginning of your end step, put a +1/+1 counter on each creature you control and a loyalty counter on each planeswalker you control.

Charix, the Raging Isle

Spells your opponents cast that target Charix, the Raging Isle cost {2} more to cast.
{3}: Charix gets +X/-X until end of turn, where X is the number of Islands you control.

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

Island

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.

Breeding Pool

({T}: Add {G} or {U}.)
As Breeding Pool enters, you may pay 2 life. If you don't, it enters tapped.

Basri's Solidarity

Put a +1/+1 counter on each creature you control.

Spara's Headquarters

({T}: Add {G}, {W}, or {U}.)
Spara's Headquarters enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Guardians of Oboro

Defender
Modified creatures you control can attack as though they didn't have defender. (Equipment, Auras you control, and counters are modifications.)

Temple Garden

({T}: Add {G} or {W}.)
As Temple Garden enters, you may pay 2 life. If you don't, it enters tapped.

Plains

Backstreet Bruiser

Defender
As long as there are two or more counters among creatures you control, Backstreet Bruiser can attack as though it didn't have defender.