Fire Emblem: Shadow Dragon/Chapter 10

Princess Minerva "Not all of the League's soldiers took Catria of the Whitewings at her word. Some insisted her plea was a ruse, a trap concocted by Princess Minerva herself Marth doubted that, though; he had seen the woman in Lefcandith Valley, and she did not strike him as a sort of conniving menace his followers feared. As the brunt of Grust's might drew closer, Marth led the League to Castle Deil, deter- mined to attack the citadel and rescue the young Medonian princess, Maria."

Begin
First things first, Warp Marth to Maria and recruit her. Make sure you have a key in your convoy. Open the gate with the key in your convoy. You can have Marth cut off the thief if your other units don't get to kill it. you will want to make for the fortress. it is a good place to hold a position against the reinforcements. The enemy thief will take an item from the chest. Make sure to kill him as fast as possible to regain it. Also the thief will open the back door and you will be surrounded.

Have Draug or Rogger sit in the bottle neck going into the fortress. If you can, let Minerva in before you guard the entrance. She will fly past the archers and straight to Marth. You can now  Switch them out if you need to. You can pick them off one by one or break their weapons and kill them off with weaker units to get experience. Be sure to kill both knights while staying out of archer range. STAY OUT OF ARCHER RANGE AT ALL COSTS. archer range is sniper range. DO NOT ENTER UNTIL YOU CAN KILL ALL OF THEM AT ONCE.

IT IS IMPERATIVE THAT YOU SAVE MARIA AS SOON AS POSSIBLE. Minerva will not join you until you save her. Really, just go save her then move Marth back to recruit Minerva. WARNING: If you don't have have Maria, Minerva will attack your units.

oooooooooo H   o     M PP  o     RoE ooo RoEoo

ooooooooEo

EEE

Anyway, just wait until it's like only one unit before Minerva, then move in Marth. Kill the unit in front of you and Minerva will automatically talk to Marth...though you must have rescued Maria first (that is partially the reason why you should hold a position like this, you need to move Marth all the way from the jail to the south entrance)

Use a thief to unlock the door to the north and kill the hero to get a Master Seal, yay! Don't use it yet, let's wait okay? Clear the few guards left near the boss and then, boss time! If you have an units to level 20 yet, use the master seal. If you used the arena in the last chapter, this should be easy (more than likely, it will be Lena)

Visit the armory and vendors to see if there's any goodies. If you used the arena, you should be filthy rich.

Nothing more to do here, seize the gate.