Dark Ritual is one of the best black cards you can have for a Magic deck. For just one black Mana, you get a net positive of three black Mana. It's an instant card so you can play it anytime, anywhere. I mean, you play one swamp, then play Dark Ritual, you can bring out a decent creature on turn one before your opponent even has a chance to act! Imagine if you had a playset of Dark Ritual cards! Four of them in your hand, plus a swamp, plus Phage the Untouchable! Play that swamp, then spam all the Dark Rituals for a total net positive of 8 Mana on turn one! Win!
Oh sorry, you mentioned it's pretty dark out tonight and I got carried away. Have you ever played Magic the Gathering?