Faceless One
The Background-commander system pairs a legendary creature with a supporting enchantment, and this is the piece built to make the enchantment half do all the talking. Every other Background-eligible commander brings its own color, identity, and text; this one brings a blank 3/3 and a color you pick before the game. The deck's whole identity is deferred to the Background you slot beside it: the enchantment supplies the theme, the abilities, and the reason to build, while the commander slot stays a nearly blank body whose only real job is unlocking a second command-zone card. In most partner-style pairs, both halves contribute something. Here one half is deliberately hollowed out so the other can be anything. A pilot who wants a specific Background but no interest in the creatures that share its keyword gets a clean chassis with no strings; a builder who wants to define an entire deck through a single support enchantment gets a commander that stays out of the way. The "choose a color before the game begins" clause is what makes this legal without breaking color-identity rules: it grants exactly one color of freedom and nothing else, which is precisely as much as a Background-first deck needs. The card is less a commander than a socket, and the restraint that keeps it that way is what justifies printing it at all.
