That equipment was his Amulet of Summoning. The amulet gave him the ability to summon an eternal grade helper, albeit by sacrificing mana cores. That ability was priceless. He didn't want to throw that ability away.
If he could transform that amulet into a legendary grade, then that would have been for the best. Without further ado, he activated the Upgrade Cell: Equipment and had it interfaced with his Amulet of Summoning.
After a brief process, he received a notification that his amulet had been upgraded.
*
Superior Amulet of Summoning (Legendary necklace).
All elemental resistances +40.
All status effect resistances +20%.
Extends the duration of all other summoned creatures to twice their original duration.
Calming wave (Active effect): All monsters of rare elite grade and below, and a maximum of ten levels above the user, will not turn hostile, Duration: 10 minutes, Cooldown: 6 hours.
