Fire Emblem: The Sacred Stones/Chapter 4: Ancient Horrors

This is your first chapter with the preparations screen. Choose your units wisely, for two of them will have to sit this fight out. Colm can't do much for you here, and Ross may be a liability if he isn't significantly leveled up. This chapter pits you against monsters, which are a group of enemies that will become common in later fights. If you want to get Lute quickly, have Vanessa fly across the river and use them to take on monsters on the island. If you want to level them up some more, use Lute's ranged magic to fell the snag on the river's opposite side, then rejoin your companions. Meanwhile, split the bulk of your party up into three groups. Have two strong units like Gilliam or Garcia take out the reinforcements that spewed from the northwest corner when Vanessa crossed the river. Have one mediocre unit go south and help Lute and Vanessa with the monsters above the river. Have the other four units go east and destroy the three monsters and the three reinforcements. Arthur could probably take them all, because his light magic is effective against monsters, but you could use weaker units in conjunction with him as well. After that, have all of your units ford the river and assign one or two to each of the non-boss monsters on that island.
 * Objective: Defeat all enemies
 * Allies: 9
 * Recruits:
 * Arthur (Automatic)
 * Lute (Visit the southern village)

Boss: Monster
The boss of this chapter, which is an Entombed, has a lot of HP. Use weaker characters to swarm him, but make sure that they won't get killed on the counter-attack. Keep Arthur nearby in case things go badly.