Upgrade Core (High)

Introduction
A comprehensive list of cores can be found here. Upgrade cores are mainly used for upgrading items level(+1, +2, etc), more info can be fond here. Other types of upgrade cores are as follows:
 * Upgrade Core (Low)
 * Upgrade Core (Medium)
 * Upgrade Core (High)
 * Upgrade Core (Highest)

Obtained

 * Craft: Basic Craft level 8
 * Field: Bloody Ice, Desert Scream, Green Despair, Lakeside, Undead Ground, Forgotten Ruin, Mutant Forest, Pontus Ferrum, Porta Inferno
 * Dungeon: Lake in Dusk, Ruina Station, Tower of the Dead (B1F), Volcanic Citadel, Tower of the Dead (B2F), Forgotten Temple (B1F)