I must say, this is an excellent example of what can be accomplished with the modding tools. The concept is smashing, and I love it to bits. That being said... It's hard as hell. XP Though that probably goes without saying. There are a couple ideas I'd like to throw out (maybe for the easy-mode Agnis when and if that becomes a thing) that might smooth out the ridges a little bit.

For one - and I'm not sure if this is intentional or not, but I think it would be a lot more helpful if the Body benifited from Kamikaze immunity as well as the Soul. A few times now, I've had rooms with a BUNCH of enemies that chase you, and my first thought (or my panicked reaction from being cornered) is to bunch them all up, pop out Dark soul and immediately Kamikaze only to kill myself instantly. On this same note, the body sharing immunities in general would be nice, because I've gotten Pyromaniac with Agnis twice as well. The soul is immune to explosions. The body is not.

Another idea that's more steered towards easy Agnis is the souls (holy and dark) recieving either the Isaac's Heart effect, or at least Holy Mantle. One of the first things I tried when I used the mod is to use the soul as a shield and block off enemies from the body, and is something I find myself doing out of instinct every so often as well.

Again, these are just a few ideas of my own. Help yourself to them if you want. All in all though, keep up the good work. Can't wait to see where this and any other mod ideas you might have go in the future. This is certainly one of the best I've seen so far.