To add a new category to a page you can click the Category button at the bottom of the page and type in the name you'd like your category to be called.
A full list of existing categories can be found at Special:Categories.
“Heretic gods are gods that come to exist in real world, rather than staying as myths. Heretic...Heretic Gods
“Due to a curse, if a heretic god is killed by a mortal who dies accomplishing this, that mortal...Campione