act 1 hell cold arrow archer mladies
https://www.reddit.com/r/diablo2/comments/etgsio/what_makes_hell_archers_so_powerful/
hedhehogs with some idiotic auras lmao
act 2 maggots lair in particular if you are skellie necro
there are physically immune ghost bosses potentially even on
normal
on hell every crooked bee swarm is physically immune
arcane sanctuary to some chars
guys resurrecting skeleton horders
packs of serpents on higher difficulties
duriel
act 3 pigmy and
hell
https://diablo.fandom.com/wiki/Bone_Fetish
swamps of gloams
https://diablo.fandom.com/wiki/Gloam
big dudes with clubs have crushing blow
https://diablo.fandom.com/wiki/Crushing_Blow
whole triumvirate/vampires. why? they have physical res
https://diablo-archive.fandom.com/wiki/Vampire_(Diablo_II)
and of course they spam spellz
act 4 I would say most annoying is corpse eating bros and one particular seal I believe
act 5 the funny charging skeleton bros & nithilak
frozen tunnels bit annoying
gloams later, Death Lords & Lister the Tormentor naturally
and of course amplify paaaaain
I recommend going SSF, no botnet, /characters [something], no Ladder Runewords, etc. as some basic melee character to HELL. it can be quite exciting. try not abuse farming and staff of teleportation charges too much.
you will soon begin to realise that you never really played diablo, you just had fun in family friendly botnet version of it (minus HC of course, which was hilarious). +you will have time to listen to all the dialogue, game has p cool lore and neat little dialogue I appreciate.
note that today you can respec, but before 1.13 if you wanted perfect build, you'd play with skills at 1 1 1 1 1 not wasting points