Yes, MU will have its season 4 this year and its season 4 site is now already up click here
More after the jump
MU Season 4 will feature the new 3rd job class.
Blade Master (Blade Knight)
Grand Master (Soul Master)
High Elf (Muse Elf)
Duel Master (Magic Gladiator)
Lord Emperor (Dark Lord)
Dimension Master (Bloody Summoner)
If you’re level is 380 or higher, you can go through a 3 stage Quest to get the change up. Only level 400 characters can go through the 2nd and 3rd stages of the quest, however, but the rewards are worth it
Season 4 will be launch on September 3 2009 however if MUtizens will support this. The patch will be earlier. For more information about the mechanics you can visit the link here