5 clones of Zeref's sat in lotus positions, absorbing mana all at the same time. This was the max Zeref could produce and control all at the same time, without getting a headache.
This method was extremely effective and efficient in time as 3 of them focused on absorbing mana to create complete Prisma Crystals, the remaining 2 clones focused on creating Pseudo Prisma Crystals. His cultivation had already increased drastically using this method.
He had commanded the clones to return to him every time they would finish creating several Prisma crystal, so it would join up to his own mana core.
Whilst this went on Zeref now began sparring with the strongest opponents in his head. The strongest obviously being The Darkness Monarch, Beelzebub and Lucifer.
Only recently, when the feeling of being drunk on pursuing power began to die down did he have more time to think about himself, he began thinking of his mother, gramps, his friends.