Saleen requested to keep watch overnight because he wanted Lex to have peace of mind by proving that there was no estrangement between her subordinates and himself. Saleen also knew that the demons could easily kill the magic beasts, and he could obtain intermediate level magic nuclei.
An intermediate level magic nucleus did not appear to be more valuable than a high level magic nucleus, their exchange rate was very disproportionate. The function of an intermediate level magic nucleus could not be replaced by a high level one.
It was just like how an intermediate level magic nucleus could not substitute a low level magic nucleus. The function of each type of magic nucleus had their own special significance. On the battlefield, an intermediate level magic nucleus was the most important strategic asset.
