There was mod that works a bit like RF Tools dimension called Mystcraft, and if you made a world say you set main block to emerald/diamonds anything valuable, it was increase the chance of instability, making all bad things, like a world effect of hunger/poison and even decay. I have not experienced in RFTools, does exist in RFTools or is just really power usage. As if at all possible I would like oregen to said unstable world and only unstable worlds.

RFTools balances dimensions with cost. So if you have expensive dimensions with diamond ore and such it will cost a lot of RF to maintain the dimension (not only create but you have to constantly keep pumping power in the dimension)

Not yet but I could do that. For 1.10.2 only though

That's fine my mod will be 1.10.2.

Is there an API that let's me get the world's traits so I can decide wether it is bad place to be, e.g. bad potions, harder mods, probably most the dimlets that bring down RF cost.

Also along with traits of the dim, I would like know the RF/t of world.

Speaking of negative potion effects, I once got a random dimension with the Instant Damage effect :/