Demon

• Priority one when you start is to fill up your roster of dudes. A good set to aim for is exactly what you might guess: two tanks, two DPS, two healers. This way if one guy gets hurt you can swap him out without losing a key role. Longer term, it's nice to spread out your resistances and damage types, so that if you meet enemies with powerful fire damage you can swap in guys who aren't weak to it.

• Good early-game demons: zombies, slimes, those weird cats that cast Guilt, most things with ranged attacks, anything that heals but especially faeries. Abbey lubbers are okay, but fall off quickly. Goblins charge way too much. Dudes that cast debuffs and such are usually trash, but crap demons can still have powerful skills (which they're just not optimized to take advantage of), so whenever you see a new one, skim through and see if it has something useful.

• Cash is tight early on. Mostly you want to spend it on fusing demons. When you fuse, the first demon acquires whatever the second demon's modifier is (you can see what that is on its character screen), giving it stat boosts, resistances, and some random skills corresponding to that modifier. The second demon dies. You can't fuse onto a demon that's already been upgraded this way. So whenever you have a passable demon and a source of a passable modifier for it, go ahead and fuse. One notable exception: when you find a Gandayah, grab it, copy Tireless onto yourself, and then ditch it. That's 25 Max SP, forever, for basically no work.

• Demons level up, but will nevertheless inevitably be eclipsed by better demons you find later on. Don't get too attached.

• As always in RLs, don't be afraid to just fucking run. Movement takes half as long as acting, and your demons can cover your escape. If all else fails, remember demons are replaceable.

• The most dangerous enemies are ones with good ranged attacks, especially AOE ones. I'm looking at you, fucking air elementals. Often these aren't even worth fighting, just leave and never come back.

• One non-obvious point about fusion: each unique demon has its own unique, stronger modifier to pass onto others. However, if you modify the unique demon itself, then that unique modifier will be overwritten and lost. Thus, you might consider leaving uniques unmodified so that you can put their cool modifiers on other demons.