Place of Power Combat
From Solium Infernum Wiki
Attacking a Place of Power is similar to attacking another legion. There are normally two rounds of combat, each consisting of a Ranged, Melee, and Infernal phase.
A significant difference is that a Place of Power can never retreat, so if there is not a winner after two rounds, the attacking legion will always be forced to retreat.
As of v1.06b, casting a successful Destruction ritual at an enemy Place of Power/Stronghold will always award 1/2 of its level in prestige. A successful Destruction ritual directed at an unowned Place of Power will always award 1 prestige.
Unowned Places of Power appear to heal at the base rate of 1 hp/turn. Owned Places of Power heal at the rate bestowed by the player that controls them.