The Vanilla skull you cannot craft, You will have to find it so you are able to craft the modded skull.
Where can you find a skull? Somewhere in the wilderness of Rivellon.

where do you find the skulls for this mod

can be added to existing saves or no?

Wand and Staff have wrong recipes. There is no need for "any water source", as it will just give you an Invalid Combination message. Just combine Magical Skull + Any Hammer + Long Branch for the Staff (replace Long Branch with Short Stick for the Wand) and you should be good to go.
Also Gloves and Boots have their recipes swapped.
Other than that, excellent mod.

lazly made my dude show more effort

@RoLaR
You don't need any other mod for the recipe to work. It should work, maybe it's not active in your mod list.

How do I craft theese? trying to combine the materials listed in the recipes but it just says invalid combination!? Do I need another mod or something?

So trying this and the Shadow Stalker, and it is a fair bit of fun, I would have some suggestions on tweaks, but otherwise these are still a blast to use as a whole. They look amazing and play out quite fun. If I had a suggestion for a future set, a lot of custom mods have these weird requirements for Summoning in certain skillsets, so it would be neat to have an armor that would put points into that so you didn't have to focus so much on that. Aside from that and maybe an In-Game way to access the recipes, appreciate how these actually make for paying attention to crafting more, using Source Orbs more, and generally making it easier to have solid gear without having to jump through 30 vendors to find one that gives a + to the right attributes.

@MartyrsDieYoung Yes

Does this work on existing saves?

Ay lookin forward to it. Think using all your sets will make a new playthrough worth it

@Zilyanna Im not that good of help, but i made a Hydro version now.
@Loser No plans for Geo. I am planning to make pyro after Hydro version.

I would like to know if you have any plans to make any more sets at all lol. I liked the finesse armor too. any plans in the work for a geo or pyro set? Or really anything lol

@RobotGodzilla if you have sometime later, could i pick your brain on how to do it properly?

@Zilyanna I have no plans to make a hydro version for now.

This is an awesome mod and love the appearance. Would you by chance be interested in making a Hydro version? i tried modding one myself but it is super confusing xD