There are plenty of awesome and fun bosses to train at when you are getting bored of the same old solo training places like Scrapyard.
If your character level is not high enough or strong enough to fight the bosses alone you can join an active guild that does boss runs everyday and they can help you out greatly however it is best practice to learn how to kill a boss by yourself so that you can get full exp and collect the drops that you want.
With the current updates, all bosses give maple reward points similar to NX that you could use in the Cash Shop, they have a special place for it where you can purchase items using your reward points earn from bossing.
I will add more information later, afk
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