For the first week, I gathered gold, took one secondary artifact, and built vampires in the castle. Skeletons weren't being recruited yet.
On day 121, I started gathering resources near the demon lair, and on day 122, I already had 200 skeletons. Then, I slowly cleared all the skeleton locations, and on day 127, I started gathering resources before the garrison.
On day 131, I easily broke through it, but I didn't have enough time to dismiss the hero and take Aina. I managed to do it only the next day, visiting the library. On day 133, Galtran (18, 12, 11, (120)) with 500+ skeletons, 20 greater vampires, 6 black knights, 7 wyverns, and a few Ainas broke through the second garrison. Ivor had nothing to counter with.
Thank you for the game.