well, seeing as you intend to have a mod where you can start with early on, perhaps add some mechanics and such based around some vanilla mechanics.for example the brewing... perhaps you could add a mechanic which allows you to brew better potions, with perhaps combined effects, longer duration, and different kinds of effects.or take a shot at enchanting, allowing the player to enchant their items with the option of allowing the player to choose what enchantment they can use.now some other mods already do this aswell, but as you mentioned, they're kind of mid to end game things, but if you were to introduce a way to do this as soon as you hit the vanilla stage of these things, people can already start with this alot sooner. now ofcourse it shouldn't be the intention to bring late game mod mechanics to early game through this and basically making an unbalanced mod. players can start early on this, but either the effects will be low of these mechanics, or there'll be alot of RNG. but the player is given the option to improve these mechanics and thus increasing efficiencynow it's quite hard to think up new mechanics that another mod hasn't done already, so alot of suggestions will be based on other mods. one of those suggestions is both ichun's Morph and Sync mod. combining the two would be a great combination, you're able to capture an entity, and remove their soul, leaving behind their body. this body can be put in some sort of container to prevent the body from decaying. through a ritual you're able to take your soul out of your body, and transfer it into one of the bodies without souls. you're able to move around and do things like the entity was able to do so, but ofcourse you don't have any items or equipments on you, as you only moved your soul. because of this, other entities do not recognize you, so hostile entities will not attack you, nor can you attack them unless the body of the entity you're in was able to attack other entities. now you're able to gain items and equipments through this ritual, but it'll require other rituals to do so. one ritual could allow you to carry items, with another ritual increasing the amounts of items you're allowed to carry. another ritual would increase you health or defense, and another ritual would allow you to wear armor. these rituals need to be done on the body when the body is in the container without a soul. as a way to prank people, you're also able to move the soul of another players into the bodies, or if you're capable enough, you're able to transfer your own soul into another player's body, while their soul has left their own body.something that I've always hated is losing everything when I die. there are gravestone mods which will store your items upon death, but they're often glitchy, resulting you in still losing your items and your experience is never stored.with the previous suggestion, you could perhaps introduce a way to transfer your soul back into your previous body that died. it'd be when you die, you leave some sort of grave behind, which stores your body. through a ritual you can move your soul from your new body, into your dead body, giving you back all your items and experience. now ofcourse you can't wait too long with this, as your dead body is not properly stored and it's decaying. when you've succesfully transferred your soul back, your dead body has some limitations, as it's dead. this means you'll be somewhat like a zombie, meaning you can't handle sunlight, you'll need to kill other mobs to feed on their flesh so your body keeps moving, but your damage increases and hostile mobs won't attack you unless you attack them. your goal would be to preform a ritual on your dead body, so the items and experience you're carrying will be transferred in some sort of container, which your healthy body can access. after this ritual your dead body will truly become dead, and will become a zombie which you can still transfer your soul into, but it'll ofcourse not have it's inventory or experience anymore. now there's a drawback... if you wait too long with this, your dead body will turn into a zombie. that zombie still has your inventory and experience, but it'll be stronger then other zombies. so you can still get back your items and experience, but it'll be a tough fight.now this is all fine and dandy, but I've really been wanting a way to easily gain back my items and experience from a previous death. so perhaps there could also be an item, which you need to have been carrying, which will transform you into a ghost after your death. as a ghost you've all your items and experience, but it's basically all locked, you won't be able to use anything of it. but as a ghost there's some positive points, as you won't get hungry, other entities can't attack you (though nor can you) and you'll be able to fly, even through blocks. your goal is to move back to your spawning point, and get into your new body. now if you're far away from your spawning point, it'd mean you'd have to travel a long way, so if you're carrying another type of item, you're able to instantly travel into your new body. this can also be done through a ritual, so you'll be able to move around like a ghost, but you won't have to die to do this. though you'll need to put your own body into a container, or that body will die. to prevent players from checking another player's base just to find out how to grief it, players are able to cast a ritual that'd prevent other players from moving around in certain areas as a ghost.now I could go on and on with all kinds of ideas, but I think I've already done a tl;dr text