From publisher blurb:
Eldritch Omens is my second collection of house rules for use with The Original Fantasy Roleplaying Game. The rules presented herein pertain to all things magical and serve as a companion volume to Bastard Sword, my first collection of non-magical house rules for The Original Fantasy Roleplaying Game. While access to Bastard Sword will aid in understanding the rules presented here, it is not necessary. You can utilize all of the house rules presented here in your own campaigns without needing to refer to Bastard Sword.
As was the case with the rules in Bastard Sword, these rules aren’t fancy or complicated. I use them because they add a unique flair to my own campaigns without complicating my life as a referee. As was the case with my previous volume of house rules, you are free to use these rules as you see fit. They are best considered as options and can be mixed and matched in your own campaigns of The Original Fantasy Roleplaying Game, as you deem appropriate.