Скачать или смотреть Fire Emblem: Sword of Seals - Hard Mode Walkthrough (English Patch) | Chapter 12

Chapter 12 is another castle stage. By now you should definitely have some promoted units. Rutger, Dieck, Lugh, and your best calvary are your highest priorities to promote. This will be good because this stage has you split up your party, so you can use Clarine to heal one party and a promoted Lugh to heal the other.

Lugh can also recruit Ray, an enemy Shaman. Ray, weirdly, does not get any HM boosts to his stats. And he does nothing Lugh can't already do so he offers nothing for us.

Anyways, have your stronger units on the right as there are fewer slots for them and your weaker on the left. Bring at least one thief but two can be useful. We need to beat this stage within 20 turns to unlock the X battle after it so we can't spend too much time going after chests. If you don't want to bring two thieves you can use Merlinus with door/chest keys to gather the treasures on the left side.

Now advance quickly but also advance carefully. You should be strong enough to take out the units that give you trouble but remember 20 turns is quite a long time, so you should be able to reach the boss and defeat him in well enough time. Not a hard stage at all, just have to pay attention and be smart.