I was discussing things such as material sinks with a friend, and came up with the following:
(The first I won't really discuss, but it was just the concept of some craft-only accessories, oh and higher amounts for missions)

Potions are expensive one use per player per floor buffs (and maybe debuffs?) I don't think we need any healing potions or status effect potions, vials and pills cover those. Potions of a similar type do not stack (Attack+, Defense+, Attack-, Defense-, Movement Speed+), and they have 1-5 star variants. Bosses, or any mobs of the developers' choosing have immunity to their negative effects. Negative effects do not harm players, and positive effects don't help enemies. They can effect all players to a lesser extent, the holder to a greater extent, one mob to a great extent, or all enemies (in a range) to a lesser extent. They can effect all damage types to a much lesser extent too, but don't expect the all-stat-all-player potions to do a lot. :)

I'll post more specific recipes later, but for now I just wanted to get this down 'on paper'.