The game is awesome, and awesomely maddening at the same time. If you just run around fusing willy nilly, you'll end up fighting bosses with the wrong party, and either need to level grind to overpower them, or macca grind to have enough to summon the demons you need, or demon grind to recruit/fuse what you need. And that's not counting "specialty" demons, where you go into a fight with all party members resistant or better to physical and electric attacks, able to cast wind spells, all the same alignment as your hero, and having at least one of each: Debilitate, Luster candy, Mediarahan.
I repeat: FUCK
I've been incredibly patient with it, though, and I have full confidence in the fact that the ending boss will probably be easy as hell, because I've over leveled to kill annoying minor bosses I didn't have the proper party for.
This is totally why I'm not sewing right now.