in theory there's about 65k seed maps say you doing lk chest for hrs each drop from the chest is tied to that map seed. so say seed 123456 drops a potion key sword tp. and say seed 123457 drops, mace, 10 gold, id, um rune. and you document each drop as some point you be able to look up what seed your on and how many map re rolls till the next hr. there was a place doing this but i don't do were it was at. think players count too. and you could do that to each chest in the game i guess...
so not quite random but did a good job at making it seem random.
think it works the same for mobs too if you kill them the same way same spot. classic is little different from lod were map seed stays the same on lod it changes
to change the seen you crate a new game on different difficultly. if you only have normal think you can make a ip game and that resets it i think...
the monsters i think there are sets say there 12 sets per seed. think that's they chest and monsters move around well the seed stays the same.
think shopping is also like this think some point you start seen the same items...
racks on the other hand stay the same as long as you click and go to it the same each time should drop the same item. things like monsters or click it on different angels can make it drop something els. casting think hydra beside it changes it too. casting like mana shield in town can change the way the rack item drops. each time you have to cast mana shield. if you dont you could get something different.
d2r they added a way to lock and look up your seed. as for lod i no idea how to do that. think there a command but you need to no the seed first. idk for that info.
odds change for chance of getting a set / unique item from rack in different patches. think 1.07 is 1in 1000 for unique and 1in 800 for set and 1.08 think its like 1/800 for unique and set don't remember.
1.07 has a broke tc class so up to 66 any items above this you need to rack.
1.08 was fixed but the odds of dropping are really bad and mf stacking is like 120k so you need dr gear to afk 1.08 well 1.07 its 4 sets of rituals will force all items to drop unique up to tc 66.
but you cant rack evrey item like bows you cant. so there like one mob is the game that can drop a windforce 08 bow and its something like 30k runs or something. one guy got it after a few runs...luky...if there like 65k seeds looks like there 2 chances for it to drop...
think if you can imbue you can get a unique item that way...
anya can give an item and some patches it a way to get Hydra Bow like 1.07 so you can craft it for the 3 socks fun stuff...you can reuse the item over and over too. imbue is broken on 1.07 too like you can add a ammy in there...