Ryan assumed that fighting the four demon generals would help him a lot. While that was happening, he wasn't gaining much battle experience. They were helping him because they were strong creatures and because their powers were useful to enhance his progress, but aside from that… Ryan didn't even need Time Skip anymore to keep all of them down. Maybe things would be different in the real world, where their vitality wouldn't be directly connected to their mana. Still, Ryan could feel that he would manage.
Beelzebub tried to enhance his body and protect himself from the spores, but Ryan's power increased more than he could do the same. Thus, he got despaired and tried to summon his creatures to increase the production of the spores, but Ryan destroyed them anyway. Soon after, Beelzebub's turn came.
Congratulations! You have become a Level one Gluttony Lord!