Chromatic Observatory - Finish the level, destroying 10 Deadly Toys using normal hits before completely killing any of them with a grip
This wasn't as bad as I thought it would be. Just roll around spamming X or Y. When they glow keep hitting them till they die. They will keep spawning, after you kill the 10th one just kill the last 3 with the grip. You are allowed to use LIGHT magic to heal in this. Don't think you can use items or Shadow magic though.