To get a Homunculus in Diablo 2: Resurrected, you have to kill a monster that drops it, and this will only happen at random. There’s no guaranteed way to get a Homunclus, but there are ways to increase your chances of getting one, namely repeatedly playing the sections of the game in which a monster is most likely to drop one.
Homunculus is so high level that you can’t get it on Normal difficulty at all. The earliest you might get one is in the Palace Cellar on Nightmare difficulty, but don’t count on it. The monster with the highest probability of dropping Homunculus is Baal on Nightmare difficulty, followed by Andariel on Hell difficulty, and then Mephisto on Hell. All bosses on all Acts on Hell difficulty, and on Acts III, IV, and V on Nightmare difficulty have a decent chance of dropping it.
If boss battles are too repetitive for you, and you’d rather farm an entire Act, then Act V on Nightmare difficulty is probably your best bet. It’ll almost certainly be a lot slower that way, but you never know, you might get lucky.
In terms of pure physical defense, Homunculus is the best shield for Necromancers, plus it offers a big boost to all resistances. It’s especially useful if you use a lot of curses (dark magic, not swear words), although admittedly very few Necromancer builds do.
Homunculus has the following list of bonuses:
- +150-200% Enhanced Defense
- +5 To Mana After Each Kill
- 40% Increased Chance of Blocking
- 30% Faster Block Rate
- +2 To Necromancer Skill Levels
- +20 To Energy
- Regenerate Mana 33%
- All Resistances +40
- +2 To Curses Skills (Necromancer Only)