- A reference guide and manual in Russian for Heroes 3.

When attacking a Titan castle, does the hero having the Sphere of Fire in the city affect the damage of the mines?

Having the Sphere of Fire grants the defender +50% damage, as the mines protecting the fortress walls are considered classic magic.

At the same time, here's the damage calculation mechanism:

The amount of damage dealt to each enemy unit by the mines that appear on the battlefield after casting the Land Mine spell is determined by the formula (10xSP + A), where A is equal to 25 if the Hero does not have the Fire Magic secondary skill or has it at the basic level, 50 if they have Advanced Fire Magic, and 100 if the Hero has this skill at the Expert level. Mines do not deal damage to defender units.

The damage from "city" Land Mines differs from "battle" Land Mines – it is not constant and is calculated differently for the game and its expansions.

For RoE:
1) If the city has only a garrison (without a hero), the damage from each mine is 55 HP.
2) If there is a Hero in the city, the damage dealt by Land Mine is determined by the formula above. In this case, the damage from the mine can be lower than 55 HP (minimum - 25 HP).

For AB and SoD:
1) If the city has only a garrison (without a hero), the damage from each mine is 150 HP.
2) If the defending Hero has Spell Power and/or the Fire Magic secondary skill such that the damage calculated by the specified formula exceeds 150 HP, then the damage from the "city" mine will be determined by this value; otherwise, the damage will be 150 HP – i.e., unlike RoE, the damage from "city" mines is never less than 150 HP. Interestingly, in this case, the mines that appear on the battlefield after casting the Land Mine spell can deal significantly less damage than the "city" mines. It should be noted that Land Mines along the Tower walls are less reliable than the defensive moats of other cities, as they deal one-time damage and can be easily destroyed by the Mass Dispel spell.

And also: will these mines affect efreets, phoenixes, fire elementals, etc.?

The rules for mine operation are consistent with third-level fire magic – all units immune to this magic do not take damage, and golems take reduced damage.

- The Amulet of Vulnerability will also definitely work (regardless of which hero has the amulet) – it removes immunity from all attacking units on the battlefield.

- The Cloak of Negation neutralizes mines, regardless of which side it is on.

- However, the Sphere of Inhibition does not isolate units from the effects of mines, although, in theory, it should, because mines are pure magic, and they are removed by a dispel spell...

That's probably all about this obscure topic...
Is it clearer now? :D