Challenge level: Easy
Challenge Name: babytree
Challenge Requirements: I'm looking to add a bit of nature to my island...pass me 64 birch saplings and I'll give you something a bit more exotic.
Challenge Rewards: 1 jungle sapling
Is the challenge repeatable: Yes
If Repeatable what are the repeat rewards: 16 Jungle wood
Reason you feel this would be a good challenge: Ok, I'm sure most of us on Skyblock have been in the situation where we have hundreds of saplings yet no use for them as we're obtaining more than we can replant. Additionally, Jungle saplings are somewhat of a rarity on SB, as around about the point where you need one or four, they're out of your price range and likely requires you to give up a item of greater worth to another player who has managed to obtain more.
Now, I in a way like the rarity of Jungle saplings, but I feel giving people one sapling would be fair.
Challenge level: Medium
Challenge Name: Butcher
Challenge Requirements: Hand me 16 raw Beef, chicken, and Pork, And I'll give you something to speed along that cooking.
Challenge Rewards: 16 Coal
Is the challenge repeatable: Yes.
If Repeatable what are the repeat rewards: 4 Coal
Reason you feel this would be a good challenge: Pork is currently nigh on useless compared to say the rewards of a mooshroom farm or even the easily-obtained cow farm, and with requirements of 16 poisonous potatoes and a saddle for solo players to achieve two pig eggs, I feel this challenge might provide a bit of use to them.
Additionally I'd imagine as players begin to form Animal farms they will have s surplus of raw meat, and the coal (for me at least) would be extremely useful for smelting things such as cobble.
Challenge level: Hard
Challenge Name: ChestMagic
Challenge Requirements: I need two enderchests to make storage more convenient - help me out and I'll give you something shiny!
Challenge Rewards: 3 gold bars & 1 emerald
Is the challenge repeatable: Yes.
If Repeatable what are the repeat rewards: 3 iron ore and 16 endstone
Reason you feel this would be a good challenge: Again, Ender eyes (villager trade) are totally worthless on Skyblock. Also, many people find themselves with spare obsidian after completing the netherportal challenge, and this could be a great way for them to use that. In keeping with Hard challenge tradition, gold is part of the initial reward.
Challenge level: Master
Challenge Name: MasterSlayer
Challenge Requirements: Time to show these mobs who's really in charge! I'll need 64 of the following: Bones, Gunpowder, Rottenflesh, Arrows, Raw beef, Raw Chicken, Raw Pork, String, and I'll also need 16 enderpearls. Good luck!
Challenge Rewards: 3 Diamonds, Ward and Chirp Music disks, and a Creeper Head
Is the challenge repeatable: Yes.
If Repeatable what are the repeat rewards: 1 diamond and a blaze rod
Reason you feel this would be a good challenge: This is essentially the mob version of topchef, and I for one often found myself with surplus mob drops. The 16 enderpearls make this a little harder though, and I added the music disks as those are ones I had trouble finding on the way to maestro, and Master challenges often reward disks. Creeper head just as a cosmetic bonus, they have no use outside decoration so I don't feel this challenge will ruin the economy in any way or provide some sort of overpowered bonus to players.
Notice that with an efficient mobtrap and a bit of luck, this can form a way for players at higher levels to repeatedly obtain diamond for their utility uses such as tools and picks.
That's all for now, feedback welcomed.