If a better option exists, it makes sense to abandon this one. The power of a Dark Shaper, relying on the Dark Element Stone and a suitable corpse to create, requires strength from the bodies used in life.
The first condition is that the materials must be beings that he has personally killed. One cannot entrust others with this task, and one cannot use weapons that are far more powerful than one's own ability, as this would contaminate the essence and lower the quality of the pet created.
Second, the high-quality origin of a lifeform is a predictor of a higher quality future for the summoned creature.
The quality mentioned here does not just refer to the level, but to the inherent quality of the creature. For instance, a regular crow and a crow king are entirely different, even if the king has a lower level.