Quote Originally Posted by Spatvark
A few days late I realise, but it's worth noting that you can do the Black Omen four different times. Go to 2,300AD and do it there, then 1,000AD and do it there, and then 600AD and do it there, and finally, 12,000BC and do it there XD

Going through four times means a ton of exp and ap, as well as lots of Speed, Power and Magic tabs + Megalixirs from the enemies within. You should be able to easily max everyone's speed, and significantly amp up your power and magic for certain characters.

All in all, if you are struggling, it's a good idea =P
This is a good idea, however you can't do it in 2,300. Queen Zeal appears and tells you that you're too late; Lavos has already won. And you can't enter.

I always do it the other 3 times, though.

Another good place to level up is Giant's Claw. Although that's not as much fun as going through the Black Omen three times.