If you're lucky enough to find Accuracy and Blessing (from opposite schools) and apply them to pigs, their first attack will be 6 times stronger (and 12 times stronger against obstacles!):D This is very significant at the beginning of the game. For jellyfish, it will be less – 2.7 and 5.4 times respectively.
Posts from What spell combinations are there?
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
I said "at the beginning of the game," when the hero is still far from having level 4 spells (cat-like reaction), but getting a level 1 spell from the opposite school is quite possible. Also, at the beginning of the game, there are few Medusas, and for petrification to work, the Medusa squad needs to have a 50% chance of killing at least one unit from the enemy squad; the probability decreases as the level of enemy monsters or heroes increases. To use an infinite supply of ammunition, you need to prevent the enemy from engaging in melee combat, which is also problematic at the beginning of the game.
completely eliminates any stack, and also restores your own
an extremely daring move