[Alneyan]

Neither the Iron Walls spell (increase defence of a fort by 200 points) nor Arcane Masonry (increase the effective defence of a fort when besieged) appear to be working.

A test involved one unit with a siege bonus of 50; despite the presence of Iron Walls (lasting ten turns), the Watchtower (defence 50) fell in a single turn. Likewise, with a mere commander besieging the tower, and another commander defending the castle, Arcane Masonry failed to repair the walls; the defence was at 0 before the spell was cast, and remained at 0, even though the besieging force was very weak (so the spell had no effect).