Songs of the Damned is actually a card I consider criminally underplayed considering how good it is in any deck that cares about its graveyard and builds it up, which seems likes at least 50% of all Black decks in casual Magic
for example, Grafdigger's Cage stops Dredge decks from putting Bloodghast and Prized Amalgam into play
Azusa combines nicely with card draw, cards that let you play lands from your graveyard, landfall, and of course, gigantic green creatures or eldrazi
Although it can only return creatures with a mana value of three or less, there are many with powerful effects that are worth bringing back if they ever get removed
Slowking ex 238/193
Alibou, Ancient Witness Alibou, Ancient Witness is a nice commander if you need new ideas