Again, the hidden tile in this scenario is placed so as to make it difficult for you to get it, but I'd be more concerned about your enemies to begin with.

You'll need Alfred to face all of the horsemen approaching from the north-east, including Goldry (again). This means lots of Pikemen. Sigma and Lambda can quite easily take care of the Fighters to the west, but try not to get too close to Aizel - as he will do lots of damage, and possibly kill one of you.

However, Aizel won't be much of a concern - as soon as Goldry is beaten, reinforcements will arrive in the form of Brenda, who joins you after this scenario, and two other Knights. They far outnumber Aizel, and will thoroughly stomp him.

The secret tile is worth going for, but its pointless letting Alfred have it - his better promotion paths don't have much use for magic, so let either Sigma or Lambda go for it.