Command Tower

{T}: Add one mana of any color in your commander's color identity.

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.

Island

Plains

Expel the Interlopers

Choose a number between 0 and 10. Destroy all creatures with power greater than or equal to the chosen number.

Perimeter Captain

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

Wall of Blossoms

Defender
When Wall of Blossoms enters, draw a card.

Wall of Denial

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

The Pride of Hull Clade

This spell costs {X} less to cast, where X is the total toughness of creatures you control.
Defender
{2}{U}{U}: Until end of turn, target creature you control gets +1/+0, gains "Whenever this creature deals combat damage to a player, draw cards equal to its toughness," and can attack as though it didn't have defender.

Tranquil Landscape

{T}: Add {C}.
{T}, Sacrifice Tranquil Landscape: Search your library for a basic Forest, Plains, or Island card, put it onto the battlefield tapped, then shuffle.
Cycling {G}{W}{U} ({G}{W}{U}, Discard this card: Draw a card.)

Forest

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.