While you shouldn't expect to connect with it all that often it will act as a Call to the Grave pretty effectively against most players
A commander like Dina, Soul Steeper can sacrifice a big creature and deal double damage with lifelink, all for just 2-3 mana
A 4/4 creature for 5 is a reasonable rate as well, though as with most of blacks best mana doublers, being a creature is a pretty significant drawback with the amount of spot removal and board wipes flying around
Overcharged Amalgam has all of this and more: its exploit ability is an instant-speed sacrifice outlet, and it gets around cards like Negate and Dovins Veto
If they are amazing in Type Four or Five Color but less so in Commander, then they may not make this list at all
After shuffling and testing over 30 different brands of sleeves, I have to admit that these Player's Choice Japanese Card Sleeves were the biggest surprise