YOU MUST HAVE AT LEAST ONE TOKEN OF SPITE FOR INVADING OR DEFEATING SOMEONE WHO INVADED YOUR WORLD USING A CRACKED RED EYE ORB! For this achievement you must join the Sanguinary Covenant. After the Executioner's Chariot boss fight in the Undead Purgatory go up the stairs at the end of the long, curved hallway which is opposite of the door you entered from. When you come to the bonfire, you will notice an NPC. You need speak to that NPC a few times. Answer "Yes" to his questions until it asks you on the screen if you want to join the covenant.
It should also be noted, there are many ways of getting the Token of Spite you need. But invading a world is much easier. Some have reported it dropping from NPC's in the Huntsman's Copse, while others find one in the bottom of the pit in Majula.
However, here is a video for those who should choose that over a text guide:
As well, here is a Google Doc (I did not make it) that some may find useful for keeping track of things.
https://docs.google.com/spreadsheets/d/1hbECOaqekNSI1LcIA0wE... If you do like it, I advise you make a copy so that if the author ever deletes it, you still have one.
Enjoy and good luck! If you have any tips please let me know.