Yeah, still having trouble finding out how to add custom items and editing drops.
meh , il explain you how teh drops work:
go to server - data - data npcdrops.tsm
in there you wil see
# npc name ( dont matter whatever you write )
npcid:rarityfactor itemid:amount itemid:amount
now , the first xxxx:xx is the npc its ID and number after that is the rarity factor
the rarity factor is the amount of times a player has to kill that monster before he gets a rare drop.
all the itemid:amount in the first line after the npcid:rarityfactor are regular drops
the second row is rare drops
hope that helped