There's the effect just from wearing it. There's also the in-combat effects, which can be "round 3" or "small chance every round, maybe limited to once per combat" or "first 3 rounds". It's complicated enough that you end up needing a giant table, and I think the (kol) wiki works fine for that. A CLI command that duplicates that table for the familiars you have could be interesting maybe, but it would still have so many familiars that it would be hard to find much.