In this case, your objective is to defeat a strong troll. Unfortunately, in the previous battle, one of your characters has been killed and you will have only three characters for this battle. At first glance, it seems an impossible battle, but you will learn how it is possible to win here.
Position your characters at a long distance from each other - have two of them fight with wolves, and have Signy take position closer to the troll. Approach to the distance that will allow you to use her special skill - Massacre and deal damage to both the troll and the black wolf.
In the meantime, deal damage as Kay and retreat to hide behind the projecting tree root. When it's Aliss's turn, join Kay and separate yourselves with a fire barrier. If the wolves try approaching you, they will receive high damage from fire.
In this case, things have taken an unfortunate turn. Signy's attacks will miss and the troll will obliterate her with a stone toss. There are two characters left, surrounded and on the verge of dying. Use Kay's and Aliss's offensive skills to deal damage to the white wolves.
Fortunately, the previously cast barrier will burn up one of the wolves, and the second one will die from physical damage. As Aliss, summon the flame demon and have it attack the troll. In the next turn, kill the black wolf and replenish armor of the demon, using one of Kay's skills.
The remaining part of the battle is very easy. As Kay, keep replenishing the demon's armor and, if necessary, use your ultimate skill. Aliss, on the other hand, should make sure that the demon is standing in the fire wall (thanks to which it will remain on the battlefield for longer). Occasionally, she can also cast offensive spells on the troll. Although the opponent is tough, he will be unable to fight through the armor and will finally fall.
Commentary: The above battle is a perfect example of the fact that you can win even a tough battle. Although all the odds were against your characters - frequent misses, starting with fewer characters, no buffing items, skillful commanding allowed them to win. You can well use Aliss's demon, replenish his armor and try to figure out your own tactics to keep winning.