(make an ice farm) "get 128 ice" reward: 64 packed ice
(create a gold farm) "get 64 gold blocks" reward: 1 Pigman Spawn egg 64 obsidian
(Kill a wither) "get 1 wither star" Reward: 1 Waither head (100k wither head from head shop at sky block spawn)
(get 1 of every passive mob) "gather 1 of every passive mob horse sheep rabbit etc.." reward: 1 of every passive mob spawn eggs
(make a vine farm) "get 128 vines" reward: 32 redstone 4 gold ingots
(get to level 2000) "get to level 2000" reward: 32 diamonds
(get to level 5000) "get to level 5000" reward: 64 diamonds
(create a shop) "make a shop with at least 5 shop chests and a [welcome] sign reward: 16 redstone 1 diamond 8 gold
(get 1 of every mob head) "gather 1 of every pasive and aggressive mob head including wither , bat , ghast etc.." reward: 64 diamond blocks
I know a lot of these challenges are way over powerd so props will need some tweeking but just some ideas i had i will probe be adding on to this list -chairm