Also, in the area before that (the foggy area with the invisible enemies) there's a Blue Tearstone Ring +1, which also increases your cast speed. There's also a Fragrant Branch of Yore to replace the one you used.

Behind him is a chest containing the Lion Mage set (chest, gloves, boots) which all increase your casting speed.

In the Shaded Woods, you'll find a petrified Lion Warrior in the ruins to the right of the area (relative to you coming in). Its hood also gives +2 Intelligence/Faith, and increased casting speed. Its low weight, relatively good defenses, and excellent elemental defenses. If you trade four boss souls to Straid (petrified guy at the top of the Lost Bastille) he'll give you his armor set, the Black set. You have to take the path to the left that allows you to jump on, and then into, the well, which leads you to a chest that contains the staff. Spoiler for potential equipment, if you want the hint: The Staff of Wisdom, one of, if not THE most powerful sorcery staff in terms of raw magic stat, can be found in the Royal Army Campsite (bonfire of the same name). Or you can do what my friend did once, get Intelligence and Attunement to 99 for max spellcasting speed and nothing else, and seeing what you can do with that. If you're wanting to go pure, or near pure spellcasting, I recommend leveling Intelligence and Faith relatively equally to 20, then likely favoring Intelligence until you hit 40/50 (the soft cap). Personally, I keep my attunement at 30 max usually (enough for six spell slots before any items), unless I want a second cast of a single cast spell like Crystal Magic Weapon without using an item, then I put it at 43.

Dark souls 2 how many attunement slots