-hookshots, to climb up quikly to the roofs.
-A bow/harpoon that shots a rope to go down the building quickly (teammates can use it too).
-Air vehicles, chopters for example =)

what do u guys think?

Why would you need a to go down buildings quickly ? You just hop off, job done. Hooks are a cool idea in theory but as it is now it forces tactical decisions and either sneakiness or balls to go for THAT ladder under fire. If we got the hooks to hop up buildings at will many of the chokepoints on maps would lose their meaning completely. Think copacabana on bootleg islands, if we could scale that radar tower building and blow it up willy-nilly there would be zero challenge in getting in.

Air vehicles have been discussed a few times, as far as i know they're unlikely to happen.

Well I know the Heli's will probably never show. I personally have made suggestions and pleas for this. And it's been well explained to me why it probably will never happen. Lot's of issues with it handling building tops and the elevation targeting issues I think. (but man they would be great!) This I think is where the Helicopter model comes from that show up on a map or two as wreckage.

I personally kind of like the idea of something to scale buildings, like a rope and grappling hook. But I think there'd be issues with defining where you could use it. And due to the intensity of battle and high ground's natural advantage that most players would use it to just stay on top of all buildings.
The devs have gone through over the years and tweaked and added ladders and even some new walkable rooftops to get up onto over many of the maps. They do a pretty good job balancing out these highpoints with not being way to advantageous for the most part. Some are really tough to get into, great to hold, butyou can still of course get hit, or mortared.

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