i mean about when can i tackle one? I tried doing the lvl1 of flower in the frost and got my ass kicked in the first room.
Metal parades are signifigantly easier than character dungeons. Metal spirits (lowest tier) commonly do single digit damage and attack only once. Metal kings can hit for around 100~200. Metal gods hit harder, with the most i've seen so far being a little over 1,000 on a crit vs a light element unit.
They are like the jewel dungeon, only easier. Basically, if your account has 15 energy and you have 5 units in your party, you should be able to clear it. I think the first time I attempted one, i still had slimes in my party (they died, but i still won).