I could only get out of the spawn and start doing something on the 2nd turn, when the scout hero, having found an Armageddon scroll, merges with it against the monks, leaving 4 which finish them off... (an Armageddon scroll for a barbarian, seriously...)

Rules for online games of HoMM3 on HeroesWorld
5.8. It is forbidden to use spell scrolls of 4th and 5th level magic without building the corresponding level of the Mage Guild (GM) in any of your castles. If the starting castle does not have the corresponding GM level, it is necessary to act according to subclauses a, c of clause 5.2.