Ranger - "Higher Vampire" [5th Campaign, 5th Mission]

In the garrison, there are 40 undead, 640 zombies, and 90 vampires. It is possible to clear it right away in the first week WITHOUT LOSSES; the main thing is to have at least 2 ents, 30 archers, and resurrection. Then, after the garrison, you can take any neutral creatures in the same way with Faidaen (except for nightmares, which might be a problem). Next, go straight to the portal to capture Apil-sin, then to the dungeon to capture three more castles, and only when you have gathered all the additional heroes, bring up the accumulated troops and drop them off for Faidaen.

Added 4 minutes later

Because in the original, bone archers accumulate very quickly.

Why? In 1.6, there is also dark energy, just like in 3.1.