It's gonna be pretty hard then to attack them directly, because Austria is unlikely to rival them due to the size difference. Do they have an ally who is rivaled to Austria? If you are still in the first age, you could use claims off of claims to fabricate on that ally Austria wouldn't defend and take land from Savoy indirectly, but that is a very heavy AE move (non-cobelligerent, inside the HRE land). Outside of that, you can hope that either Austria loses the Emperorship, gets so thrashed that he wouldn't defend anyone, or that Savoy makes an ally outside the HRE who you can attack.I'm outside, Savoy is allied to Austria. It is after the Shadow Kingdom, but I took their Italian provinces before it fired, so they're in the Empire. I'm large enough that I don't absolutely need Austria to defend me, but it would be nice to get a little bigger before I throw them by the wayside.