HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

With the first save, shift+f2 indeed doesn't work correctly. It should have removed the garrison copy, not the visiting one. In the second save, I managed to fix it like this: Move Damakon away from the castle - a clone of Astral appears at the entrance. Skip a turn (since Astral has no movement points left), select the Astral clone (focus on it), and move away from the castle. Hover the mouse over the castle entrance (without removing focus from Astral) - the first shift+f2 heals the corruption, and the second shift+f2 removes the Astral clone. These two examples are new to me; I will find a correct way to fix them...