>>3830036
Your familiar gets buffed near the start of chapter 3, and is really strong at that point at very useful for all of chapter 3 and majority of 4. It does start to fall off in scaling the further you go.
BUT
By the start of chapter 4 your elemental summon gets upgraded and its a massive improvement and is extremely strong for the rest of the game.
Here is both familiar and fire elemental summon unbuffed. If you buffed them you could get atleast 10 more AC and Attack bonus out of them. I remember getting my air elemental to near 60 AC