( This writing is the original work of percy1105 in MWO Forum. If you have more to share on this topic, please feel free to ADD your words. )

yeah tunel U, U II, M, these are really good places where u can find skill book 30+ [ except skill book 36 III u must find from boss 38 in hawk fall or spirit tomb or elite in beast camp].

in this map; its not too bad but i can say that its harder than beast camp because mobs stay close to each other . and elite Scorpion is hard because he has skill posion which cause 210-350 hp in few sec[ i forgot how many sec it was. sorry] and the rat has skill that decrease ur phy attack and def . so its dangerous too. u can kill them at level 36+ but its really hard because u need at least armor 38 [ more def] and u should hit and run . and don bot where elite may respawn.

tunel U has mobs level 35 to 37
tunel M and tunel U II are harder than tunel U , mobs are level 39 to 40. elite 40 here is harder than tunel U. but its good because u can find seal royal prison and technologic stone i found many technologic stones here and seal royal prison[ ticket for going to royal prison intsance where u have to do quest 40+ but mobs are really hard even they are level 42 to 47 but their hp are 60k+ and guard <==not boss nor elite; they are special mobs but their hp are 1mil6 to 1mil7 and they are ur quest - u have to kill them].

BOSS.. in the middle of tunel M; we has a special boss he is range boss [ he look like zaman in royal prison instance but the point is he is boss haaa and his speed attack is too high. he fires around 2 laser per hit. so ... i could not kill him even my other friend[ tanker] def up to 530 still died… lol but anyway at that time we don have healer so we don know but maybe with healer we can kill them.but i think its hard . and level should be 50 [ 3rd class].