There are just 17 cards in Death Toll that can trigger a Rendmaw to produce crows , which means you're just not likely to get more than a few crows out in any given game
The other huge upgrade that isn't a Vampire is, of course, Skullclamp, which if you're lucky enough to find / stick on the battlefield will draw you all the cards you need to close out the game
Mirage, Super Recruiter also benefits from having another Super in play in order to draw a card
Actually, Un-sets are probably the single weirdest Magic product on the market, filled with silver-bordered cards that aren't legal for tournament play and brimming with obscure references and inside jokes
Even so, there are only a few commanders who excel at generating and using energy, so if you are brewing a Commander deck, youre going to want to take a look at these powerful creatures