Bone dragons... also require the "Snake Strike" spell to be available in the city, and the hero to have the Nature magic skill upgraded, or "First Strike" and the Chaos magic skill upgraded.
... 1 combo - a set for defense, the second - a set for attack.
... mechanical golems are only good against creatures with "First Strike", but where are such creatures to be found, on level 2?
... all of this outweighs the disadvantage of hydras in their slowness, which is eliminated by "Haste", "Cat's Agility", and "Vampire Touch".
Справочник по НоММ-4 http://handbookhmm.ru/pamyatka-dlya-heroes-iv.html
Памятка по НоММ-3 http://handbookhmm.ru/pamyatka-dlya-homm-iii.html
и HotA http://handbookhmm.ru/vyishla-obnovlennaya-pamyatka-dlya-homm-iii-hota.html