Do revenge spells work?

 Regarding "whether revenge spells work," yes they do, and the extent of their effectiveness is dependent on some factors, top of which are the experience of the spell caster, the intention of the caster, and how the spell was cast.

https://www.fastmr.com/public/pgs/revenge_spells__spells_to_get_revenge_on_ex.html

While revenge spells are classified under black magic spells, it doesn't mean you can use them however and whenever you like. While it is true that some inexperienced spell caster cast black spells for revenge either out of pity for their clients or out of power drunkenness to make the target suffer, Spellcaster Maxim noted that that's not what magic spells are intended for. Such spells often don't go as intended because of potential retaliation or kickbacks that trail them.