Goblin Dungeons

Alternates between EXP potion dungeon and Gold dungeon. On Sundays, both are available.

You get two attempts for free, per dungeon, each day. If you want more attempts then you have to pay for them with crystals.

Extra chance Crystals cost
1:st 70
2:nd 70
3:rd 80
4:th 110
5:th 140
6:th 170
7:th 230
8:th ???
If you fail an attempt (because you picked the wrong difficulty, or such) then you get to try again. Attempts don't go to waste.
There are two recurring, standard events that give double drops in Goblin Dungeons; "Goblin Dungeon 2X items chance event" and "Daily Dungeon 2X items chance event". Tap the event (gift box) icon on the home page and watch for these events. If you want to burn some crystals for extra XP potions or gold then during those events is the time to do it. Tip by AzakaZero
Remember to sell the chests dropped in Goblin Gold Dungeon in the guild shop to get the guild sell gold bonus. Tip by AzakaZero

Heroes' Boot Camp Dungeons

One of these is available each day, with all 3 available on Sundays.

Sword Camp

Enemies here are immune to Magic damage.

Heroines' Camp

Only female Heroes can enter.

This dungeon drops Almighty Earrings pieces, and as you will no doubt notice, you need a ton of Almighty Earrings, they are an essential part in many types of gear all the way up to the gold hero tiers. Try running this dungeon on "Hard" difficulty, rather than "Nightmare" and up, to get more earring pieces. Tip by AzakaZero

Magic Camp

Enemies here are immune to Physical damage.