gain life draw a card mtg Life, Cards Deck Drogskol Reaver · Double Masters

Fleshtaker both gives you a sacrifice outlet and lets you scry, which can be useful to help prepare to sacrifice a Junk token or use Paladin Elizabeth Taggerdys attack trigger

Blitzwings impact isnt groundbreaking, there are definitely better mono black Commanders out there that cost less than 6 Mana (Sheoldred, the Apocalypse being the latest hype Commander)

Korvold, Fae-Cursed King Korvold, Fae-Cursed King costs three colors of mana and its more expensive than Mayhem Devil overall, but the benefit it provides is huge

So, they can be solid creatures to help cards like Padeem, Consul of Innovation or Organic Extinction

It gets to do this on attack, too, which means Kefka is a great value engine over time

Until then, may your Fates be illuminated