The /challenges are really cool and give incentive to reach goals. The rewards are nice but could use a little tweaking since some of them give xp levels, and those aren't very desirable. One of the challenges rewards the player with 4 dark oak saplings and I think replacing some of the other rewards (e.g. xp levels) with the other sapling types increases incentive to complete them. New players often look for different saplings so it would be a great way to let them progress this way instead of checking out shops or using the trading villagers at /warp trade. Let me know what you think
support, I did not ever really like xp rewards because of the large presence of grinders on the server and how easy those xp levels are to get because of that.