Check the calendar for the next new moon, and plan to do this dark spell on that night. All you need is:

1 black candle

A sharp tool to scribe the candle

Piece of onyx or jet

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.