Bolass Citadel FINAL FANTASY: Through the Ages, Rare Limited: 1.0 If you can cast Kefkas Tower (Bolass Citadel) and have some good lifegain elements, it can be fairly strong
Automaton can also benefit decks that arent tribal themed, like strengthening Talrand, Sky Summoners Drake tokens
And as someone who has cast Boom // Bust on a Darksteel Citadel plenty of times, there are a lot of options to choose from
Even to the point that most people ignore rares and mythic rares to build their entire deck around cards like it
Thats not much to write home about
Of the black legendaries in the set, I really love Shadowheart, Dark Justiciar, who is an excellent Commander and card in the 99 of decks with big creatures