Tokubetsu Missions (特別任務) are a Permanent / Training Mission Type only available during a short period of time, typically during special occasions like anniversary. There are three types of Tokubetsu Missions:
Forge Spirit Dungeon[]
Forge Spirit Dungeons (オキタエールダンジョン) guarantee one specific type of Forge Spirit from chests each time you run it. The stage has four chests, with each one containing a Forge Spirit. This means each stage will always rewards four Forge Spirits, however the rarity of the Forge Spirits does vary. There is one dungeon for each of the four Equipment types (Ring, Bracelet, Necklace, and Earrings) and each one costs 80 stamina.
Life Crystal Dungeon[]
Life Crystal Dungeons (生命の結晶ダンジョン) guarantee a significant number of Life Crystals (about 50 ~ 90) for only 60 stamina. This dungeon is by far the most efficient source of Life Crystals in the game, however there is a limit on how many times it can be done when available. This limit is typically 6 times a day. Players should ensure they run the stage the maximum number of times for each day the campaign is active.
High Ampule Dungeon[]
High Ampule Dungeons (アンプルゥ・上 ダンジョン) guarantee 1 of each High Ampule each time you run it. This dungeon is one of the few sources of High Ampules in the entire game, however there is a limit on how many times it can be done when available. This limit is typically 7-8 times a day. Players should ensure they run the stage the maximum number of times for each day the campaign is active.