Reminds me of the Judges Guild "Universal System" where they had a lot of weird stats in their books, often with some made-up rules, just to avoid any issues with D&D at the time (late 70s/early 80s, I think).

Event went so far as to have three-digit stats, stating that the first two are the regular ones (to correspond on the D&D 3-18 range) and the last is "how often you can use it without having to roll for a stress test".

If you're going that unusable, you might as well write for your own or a non-litigious system and let the people convert it themselves. It's a lot of homework anyways…

For example, World of Warcraft has had the virtually identical Arcane Missiles spell for nearly twenty years now, and Terraria even had the identically-named Magic Missile for over a decade already.

In trademark law lack of enforcement can lead to the trademark becoming genericized, which is why words like Aspirin, Videotape, or Escalator are no longer trademarks but regular everyday words.

If you never enforce your IP rights despite being well aware of violations, and even actively promote use of it by third parties, at what point does it stop being IP and become common culture?