I've gotten some questions about this so wanted to mention: While this video is focused on soul drop recommendations, the Rare Ring DOES WORK for items! It doubles the chance of both Common and Rare item drops.
You know what? I'm really glad bloodstained gave us the power to upgrade yellow souls into grey souls. Because it deals with my worries about missing out on something and instead just gives me a "Get EVERYTHING" fixation. Which I already have, so no big deal.
Fun fact: Mandragora is not only powerful due to its ATK, but also because it deals stab and cut damage. If the target has a weakness against two physical types, they'll take 50% more damage than usual. There aren't many souls with two damage types in DoS.
Just recently beat Dawn of Sorrow and I'm so irritated that upgrading to death's scythe, valmanway, and balmung lock you out of getting the chaos ring. To anyone reading this, if you're gunning for the chaos ring, do not use death, abaddon or gergoth's souls for these weapons until after you've claimed the ring. If you want a maxed out weapon, just take the katana path, it doesn't require any boss souls.
The Catoblepas soul is really useful. A lot of enemies are weak to petrification and once they're petrified, you're free to finish them off at your own pace. This soul is really helpful in dealing with a lot of common enemies throughout the game.
Don't worry I went to work immediately farming zombie souls to turn brass knuckles into cestuses to then resell to hammer so to then buy the soul eater ring
I used to grind Ghost Dancers for ages to get the maximum luck buff for my playthroughs before I learned that luck was completely broken. I couldn't believe I wasted so many hours across multiple playthroughs doing something utterly pointless after finding out. I had always felt like it really did increase my drop rates significantly, but it was nothing more than a placebo.