While naturally costing just white mana, Kenrith has five abilities, each one with a different mana cost and color commitment, to help give you an advantage in your game
Black offers you so many options for exchanging resources for power, and Toxic Deluge offers an extremely efficient sweeper at the cost of some of your life total
While not as widespread as Summon: Choco/Mog just yet, it is seeing regular play in 5-0 lists
If your goal is a playable collection, boxes make sense
Chocobos are to Final Fantasy as Yoshi is to the Mario series
They allowed you to tap for one colorless Mana without any pain at all, but if you were to tap it for either color of colored Mana, it dealt one damage to you