“At long last, Altea was free again. Marth took the League to Helena Castle in the north, an old fortress and key supply point during Doluna and Grust's occupation. There he meant to seize the last of the enemy's gold and provisions but Grust would not give up the castle without a fight...”
Helena Castle (マクロニソスの城 makuronisosu no shiro, Castle of Makronisos in Japanese, or Prisoner of Helena in the Europe version) is Chapter 17x of the game Fire Emblem: Shadow Dragon. To gain access to this chapter, finish Chapter 17 with 15 units or fewer alive.
Etzel appears towards the south after the start of Turn 1 of the Enemy Phase, but only if the south-eastern room is still closed. Just ignore him, and he'll join at the end of the chapter (he does not move, so he is easy to avoid). However if you opened the south-eastern room during Turn 1, Etzel won't appear and you won't be able to recruit him.
There are 5 locked rooms in this map, so bringing a thief might be a good idea. Also, the boss room will automatically open as soon as you enter the aisle where Etzel is. Shown below are the contents of each room:
- Top right: one chest containing a Warp Staff;
- Middle right: one Manakete with a Firestone;
- Bottom right: one Mage with a Blizzard Tome;
- Top left: one Bishop with an Elfire Tome and a chest containing a Longbow;
- Bottom left: one Knight with a Javelin, one Bishop with a Fire Tome and a Fortify Staff, one stationary Bishop with Swarm, and a chest containig a Wo Dao;
- Boss room: one Mercenary with an Iron Sword and another one with a Steel Sword, one Manakete with a Firestone, one Sniper with a Silver Bow, a chest containing a Wing Spear, and the boss himself, Dactyl.
Makronisos is an island in the Aegean Sea. In ancient times, it was known as Helena.