After the attack on the arena in mission 1 for Necropolis, the screen suddenly darkens, and the "Drain Life" spell, which was working just now in the battle, is no longer selectable in subsequent battles. There is no way to choose a path, and the hero is only level 6, and other blood spells continue to work. Immediately after this, the necromancy scale button stops responding, and only when it reaches level 2. In short, to summarize: "Drain Life" is no longer selectable, the necromancy scale button does not light up, and it stops responding when it reaches level 2. Is this a bug, or am I doing something wrong? Thank you in advance.