Cayth, Famed Mechanist Cayth, Famed Mechanist may seem like the odd one out in this list, but shes deceptively useful in an energy-based Commander deck
Since part of the resource loop is to Summon "Bullet Train", "Citadel" would always have a way to Summon itself from the GY, meaning it could chip away the opponent's resources, while the player would lose none
While there is a bit of tension between drawing a filter land and another colorless source or two, they amplify your actual colored mana while fixing for colorless
For the Buster Sword, I knew immediately that I wanted this to be the FINAL FANTASY VII intro screen
It has a +20 weakness to fighting type Pokemon, a -20 resistance to metal type Pokemon, and free retreat costs