Commanders that are *almost* slam dunks

What are some commanders that you would build in a heartbeat if they worked just slightly differently?

I've always lamented that Toshiro Umezawa's ability didn’t also apply to sorceries. Spellslinger isn't really a theme that's associated with mono-B, so Toshiro's effect is rather unique and interesting.

But then you look at Black's selection of instants, and outside of spells that just kill things, the selection is dire. There’s some card draw, a handful of niche/limited reanimator pieces, the odd ritual here and there, and an assortment of other odds and ends. There just isn't enough quality or volume to build a theme around anything other than just killing things.

The only way to incorporate actual wincons that are related to the theme of the deck that I can think of would be grinding everyone down with Blood Artist effects and heavy board control, and if you want to win with Blood Artist, why not just run Aristocrats instead?

If it were instants and sorceries, Toshiro would be able to do a lot more interesting things that otherwise couldn't be easily accomplished in mono-B. Breaking timing restrictions on sorceries might've been kinda problematic back in the original Kamigawa block, but these days there are enough commanders that can do that, to the point where it's probably not that big of a deal.

Any other commanders you wish worked just slightly differently?