All of the locations of where you can get all skill tomes for all classes in Celtic Heroes
|Fingal's Cave:||Dunskeig Sewers:||Carrowmore Tunnels:|
|Ice Blast||Skewer||Sharpen Weapons|
|Bless||Defensive Formation||Shield Wall|
|Shatter||Explosive Arrow||Fire Attunement|
In my experience farming in Fingal's Cave, any mob can drop a manual or a ring. I've found Greater rings from killing 1*s. Another thing I've found is that 5* bosses seem to drop a manual or ring 100% of the time. Also, they never drop anything below a greater ring. I've killed a good number of 5*s, as well as my friend, and always gotten drops following this.