To play whole undead army you need sacrifice. It is a MUST!
Once you reach dwarves land you can sneak into demonis for black knights and necromancers (awesome unit, i nearly lost battle because of them when fighting againt this undead boy on swamps, 60n raising 40n? OMG!)
Both vampires suck as much as werewolf sadly but you can get them easily from coffins.
Cursed ghost are great.
Zombie are tought and hard hitting but no interesting abilities.
Skeletons archers can pump tons of damage but die easly.
note: You will miss animate dead spell from homm3
, using sacrifice all the time can get boring. I know because once i reached dwarves land i rushed to demonis to get demon wife (impossible fight, thx god for Armageddon) and demon army and now in elves land i am using sacrifice a lot.
Interesting idea try it and post progress
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