Before casting any dark spells, think about your motives and reasons. Basically, these are the kinds of spells you would use if someone has already wronged you in the first place. That's their purpose and they function based on that relationship with a person.
Reflect and Revenge
Mirrors are very powerful for returning energy back to someone, and are perfect for revenge spells like this. You'll need a few supplies:
If you can, cast this spell on a Saturday night. First write the person's name on the face of the mirror is big letters, then set the bay leaf over the name. Wrap the mirror and leaf in ribbon a few times, then add a generous pinch of ash over the leaf. Wrap a few more times and then tie with a solid knot.
Place one hand on either side of the mirror, and say:
From me to you,
Comes back times two.
Keep the wrapped up mirror charm under your bed, until you feel that your revenge has taken place. Don't leave it forever though. Once some bad luck has fallen on your adversary, remove it and dismantle the spell.
Black Moon Revenge Spell
Check the calendar for the next new moon, and plan to do this dark spell on that night. All you need is:
Carve the name of your target into the candle and set it into a candle holder. Focus on the wrong this person did to you, and watch the flame burn. When the candle has melted down enough to start melting where you wrote their name, take it out of the holder and drop several drips of melting wax over the stone.
While the wax is still soft, mark the person's first initial into the wax then let it cool and harden. Let the candle finish burning down, and leave the stone in a safe place (but out of sight) until your revenge has occurred. After that, bury the stone in the earth to end the spell.
There are also some new Voodoo revenge spells, if you want a little different flavor to your witchcraft.