Lvl 2: Free access to mush room, +4 endu
Lvl 3: ^, free access to vd2, +6 endu
Lvl 4: ^, free access to sand and argos room, +8 endu
Lvl 5: free access to everywhere in VD1-3, +10 endu
Upgrade idea: Bring 2 scs to a npc and he will combine them to lvl 2, bring lvl 2 sc and lvl 1 sc to a npc and he will combine it to lvl 3, etc.
suggestions are welcome