I have a few suggestions for lucky blocks. Nothing big, but things that I think would help add more content and opportunities for players.
Witch Kit - This kit could have various potions, such as damage, weakness, poison, and slowness as an example. Currently there is a healer kit and a scout kit, but there are no offensive potion kits. I think this would be really fun to play with and give more variety to the kits.
Fallen Angel Achievement - I struggled with a name here, but the name is easy to change. My idea here was an achievement for successfully breaking an elytra in lucky blocks. Now that elytra's have low durability when found in lucky blocks, this means the achievement would be accomplishable in a relatively short amount of time. I think this would be a great addition the the medium difficulty achievements.
Lightning Wand Lucky Blocks - The wands have always been one of my favourite parts of lucky blocks, but it has been a long time since I have seen any new ones. The ability to summon lightning on enemies is something that could really spice up a situation. There is currently no way to summon lightning, aside from opening an unlucky lucky block. The ability to throw lightning with a wand, or even shoot lightning with a bow, would be really fun.
Slime Boots Lucky Blocks - I am no developer, so I have no idea the practicality of implementing something like this, but if it were possible, having slime boots (or bouncy boots) would be extremely fun. I got this idea from the tinker's construct II slime boots. How they work is when you fall far enough to take damage, instead of taking damage you bounce as if you landed on a slime block. Like slime blocks you can hold space or shift to stop from bouncing. I personally think these would be very practical and unique, and I think we can all agree that at the very least seeing players bouncing around the map after falling from great heights would be quite entertaining.
P.S. I am new to writing on the forums and I have no clue how people make the spoiler drop down menus. Hopefully you don't mind mine not having them!