Doran, Besieged by Time

Each creature spell you cast with toughness greater than its power costs {1} less to cast.
Whenever a creature you control attacks or blocks, it gets +X/+X until end of turn, where X is the difference between its power and toughness.

Sandsteppe Citadel

This land enters tapped.
{T}: Add {W}, {B}, or {G}.

Swamp

Command Tower

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

Forest

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Plains

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Rat Colony

This creature gets +1/+0 for each other Rat you control.
A deck can have any number of cards named Rat Colony.