There are different paths that lead to Lavos. One is the bucket in the upper-right corner in the Bend of Time. One is flying the Epoch to 1999, the Apocalypse, and the other is going through the Black Omen (the Ocean Palace, which takes a heck of a lot longer). Now, here are the tasks that you can do to level up before fighting Lavos:

• 600 AD: In the Middle Ages, a woman's sheer determination brings a forest back to life...
  
  
• 600 AD: A fugitive in the Middle Ages, Ozzie, maintains an evil hideout...
  
  
• 2300 AD: There's a task to be done in the Future, where machinery originated.
  
  
• 65000000 BC: And there's a very special stone that can shine its light on each generation, from the distant past to the far future...
  
  
• 1000 AD: There's the ghost of a lofty knight, slain by Magus in the Middle Ages, who haunts the present...
  
  
• 600 AD: There's an object in the Middle Ages that sparkles like a rainbow...
  
  
• 1000 AD: One of your party members is close to someone who needs help... Find this person... fast. (this one can only be done after the previous one in this list)
  

You can do these in any order you wish, although a couple of them are interconnected. If you want to skip them and go straight to the end, click here.