I dont want Jump as part of Combat, but I wouldnt mind it as part of the "Event", you fight a boss on ground floor, and then when it goes into its "Second Phase" it rises up, and you have to "Jump" up the building across rocks, ledges or what have you to get to him again, so its not combat related to the mob but environment event related, i think be kind of cool.

I dont think falling damage is needed because you shouldnt be able to jump off high enough places that we cant already fall off now. I dont want people jumping down cliffs, even if they die lol.

Environment exploration is great idea!