The only Weekly Dungeons that currently exist are the Gardens and they reset daily at 8am GMT+8.
Gardens[]
Each day, a different Garden dungeon will be unlocked and players can access the garden for 1 hour at a time of his/her choosing. The dungeons typically have 2 difficulty stages with the more difficult dungeon yielding higher rarity Spheres.
Dungeon Schedule[]
Monday
Flower of the Inferno: Can capture Fire EXP Units.
Tuesday
Glow of the Blossoms: Can capture Light EXP Units.
Wednesday
Flower of the Frozen Lake: Can capture Water EXP Units.
Thursday
Blossom of the Dusky Forest: Can capture Dark EXP Units.
Friday
Flower of the Green Fields: Can capture Nature EXP Units.
Saturday
Blossom of Gold: Can capture Coin Units.
Sunday
Blossom of Gold: Can capture Coin Units.