One of the most famous black cards ever printed is Dark Confidant, a creature that draws you an extra card each turn, so long as you lose life equal to the cost of the card
This lets you set the tempo early on in the game, forcing them to recast important pieces of their board
Although its banned in EDH and Legacy and restricted in Vintage, it would be a shame to not mention it when talking about infinite combos
The scary part is that Ocelot Pride is still just scratching the surface of its potential, currently in about 7% of Modern decks
After all, if you kill your opponents creature, the fight spell or ability loses its targets and cant resolve
If you haven't cast a spell this turn, you may cast that card