The best place to train from level 40-50 is Zipangu: A Night in the Forest. This map has those paper lanterns (93 EXP) and the Dark Foxes (110 EXP). And there is a HUGE spawn of them. Here is the best organized party to train here.

1st Charechter: Preferably Assassin With Haste, If not, Then Hunter that knows how to jump shot, If not a hunter, then a Bandit would work as well.

2nd charechter: If you got a Assassin OR Hunter as your first charechter, then a bandit or a I/L Wizard would be good here. Keep in mind that a Page/Spearman would also be OK here, but only if you cannot find the first selected choice.

3rd charechter: This would definently be a fighter (MUST have Rage). If you cant find a fighter, then almost any class except warriors can work.

Here was my party:

1. Assassin w/ haste

2. I/L Wizard

3. Fighter

I got from level 44, to 46 in about 5.5 hours. Also, the drops here are really good. In the 5.5 hours that I trained, I got 2 60% 2h axe attacks, and 1 oaker shoulder pants, and 2 lvl 35 bowmn pants. The money is also good, ranging at about 100-200.

So anyway, this is the best training spot, if in a party.

One more thing, this is a good way to position your party: The assassin should kill the monsters at the far left of the map, the I/L should be right in the middle, helping the fighter or the assassin if nessacery, and the fighter should be at the far left, where most of the lanterns spot. The assassins should mainly kill foxes, while the Wizard and the Fighter kill the Lanterns.