Heroes 5.5 WarGame Edition - Tactical Edition.

A zero-cost spell would take up space in the spellbook, which would be inconvenient. And its actual usefulness is likely to be very low. Regarding the technical aspect, there is also a problem – I don't yet know how to add such spells to the game, and whether it is even possible, and if so, how. In the Haven faction, there is a fist spell that costs 3 mana, in the Chaos faction, there is an arrow spell that costs 2, and in the Dungeon faction, there is a curse spell that costs 2. Thus, enchanted attack can be translated into a very economical mode.