Can Cassis Crista be used simultaneously with Dragoon Helmet?, or by putting one the other would be removed?
I think you can use both at the same time, but only if you use the lightweight attribute for the dragoon helmet. I have not personally tested it though, so take it with a grain of salt, this is just what I heard from someone else.
if you are dicephalic like misrus i think you can. you should try add pd mask too if you are tricephalic like cerberus.