v.154 – Sword Art Online Update Notes

Same here.

Mystic Von Leon's Nightmare: Medal, Req. Lv. 75, STR +10; Weapon ATT +2, Magic ATT +2
Mystic Arkarium's Nightmare: Medal, Req. Lv. 75, INT +10; Weapon ATT +2, Magic ATT +2
Mystic Hilla's Nightmare: Medal, Req. Lv. 75, DEX +10; Weapon ATT +2, Magic ATT +2
Mystic Zakum's Nightmare: Medal, Req. Lv. 75, LUK +10; Weapon ATT +2, Magic ATT +2
Mystic Horntail's Nightmare: Medal, Req. Lv. 75, Max HP/MP +500, Weapon ATT +2, Magic ATT +2
Mystic Gate Master: Medal, Req. Lv. 100, All Stats +10, ATT / MATT +4, Untradeable

Open 100 or more random gift boxes - Mystic Field Researcher: Medal, Req. Lv. 75; STR +5, DEX +5, INT +5, LUK +5, Weapon ATT +3, Magic ATT +3.
Open 200 or more random gift boxes - Mystic Field Master: Medal, Req. Lv. 100, STR +10, DEX +10, INT +10, LUK +10, Weapon ATT +4, Magic ATT +4

But then if Mystic Field=Mystic Gate, then Mystic Gate/Field Master is just listed twice for no apparent reason?

Nexon and proofreading their Patch Notes do not go hand in hand.