Facebook: Block Event Invitations From a Specific Friend

If you no longer wish to receive event invitations from a specific friend, you can follow these steps to block future invitations:

  1. Select Privacy Settings from the dropdown menu in the upper-right corner
  2. Select Blocking from the left menu
  3. In the Block event invites section, enter the names of friends you do not wish to send you event invitations

Should have done this years ago.