Hey, im new to commander
Secret cards seem to be an invention of the English version of the TCG, as all cards released as "secret" have been included in the normal set numbering in Japanese
A set can go from positive EV to negative EV in less than a weeksometimes even overnight
Because youre in Black, you can probably benefit from every single one of those downsides, so Rankle can be incredibly powerful in the right decks, and if theyre your commander, then theyre probably in the right deck
Sword of Forge and Frontier Sword of Forge and Frontier has its main role as a powerful equipment with extra lands as a side effect, and you can play this in non-green decks as well
Amethyst If you like controlling what your opponent can do, and sneaking past their defenses, all while gaining huge card advantage, amethyst is the ink to check out