CotW? I know of only one card that fits that abbreviation: Call of the Wild. I don't think this is what you meant. Chalice of the Void, probably, or Crucible of Worlds? Either is one keystroke off and both could potentially fit in a prison deck like you seem to be suggesting.
For aggro prison, I see nothing Mono Black has to offer over various multicolored Fish builds. Why would I trade Tarmogoyf, for example, in exchange for a lot of cards with
in the cost? Adding even one more color, like in SS, will grant superior disruption, better lock parts, and a faster clock. If I had to pick a single reason why Suicide Black died, it would be that fetchlands got printed and now the disruptive aggro decks have three colors instead of one. And as for including Bitterblossom in Fish, it doesn't seem that good in a format without mass removal. Wrath of God and Volcanic Fallout are the two best arguments for using Bitterblossom in Standard.
As for a Braids deck or whatever, how would that be better than Stax? This is clearly the other place where Bitterblossom could potentially shine, but I'm not sure what it really has to recommend it. You could try it in a black-heavy Stax build, potentially with Smokestack and maybe not Braids at all. This would let you leave the Smokestack on one counter and basically pay 1 life per turn instead of sacking to it, or even let you ramp to two counters relatively painlessly. It would also provide a sort of slow clock in the absence of a robot. Still, if Stax is indeed subpar right now, I don't think that a lack of ways to make Smokestack asymmetrical or a lack of ways to generate a clock have anything to do with it.
