Problems appeared even before that Noah could start experimenting.
Rank 4 magical beasts were powerful, Noah couldn't casually kill them as he did with those in the third rank.
It took a bit of thinking to find the method that would leave their bodies as intact as possible.
The Mental tremor spell was simply too strong now that Noah had a rank 4 sea of consciousness, his mind could affect the material world, the shockwave shot from his eyes would just reduce the beasts' brain into a pulp.
Noah had to find a subtler method to kill them, something that wouldn't waste that precious material.
In the end, he decided to use the Death area spell and the Ghostly claws spell.
Both spells had been empowered after Noah triumphed in the Earth Tribulation, those that once worked as supportive attacks now were threatening tools in Noah's hands.
