Source: Arcana Unleashed
General Feat (Prerequisite: Level 4+, Familiar Friend Feat)
You gain the following benefits.
Ability Score Increase. Increase one ability score of your choice by 1, to a maximum of 20.
Otherworldly Power. When you cast the Find Familiar spell, you can imbue your familiar with otherworldly might, which lasts until you cast Find Familiar again. While imbued, your familiar gains the following benefits:
Energy Resistance. Choose Necrotic, Poison, Psychic, Radiant, or Thunder damage. Your familiar has Resistance to the chosen damage type.
Phase Walk. Your familiar can move through other creatures and objects as if they were Difficult Terrain. If your familiar ends its turn inside an object, it is shunted to the last unoccupied space it was in.