Agarthan fortresses

[llamabeast]

Yep, I reckon it's because of the border mountains. Hover your mouse over the "mountain" symbol, and some will say "border mountains", some just "mountains". Border mountains don't count as mountains for the purposes of fort building - or of movement, in fact (this confused me for a long time).

[Yrkoon]

Ha, thanks for that - I never paid attention to the difference between border and normal mountains. And the movement also baffled me, but now I understand.

[Valandil]

Actually, I had never thought to try it. Does eg. thunder strike work underground?