This isn't useful on its own, but has a lot of potential applications by allowing a type of movement that blizzard usually tries to restrict.
First, use the engineering tinker "nitro boots." Since cata, these have a high chance of failure. The most common failure mode is to rocket you very very high into the air. This can occur indoors, in bgs, and in instances.
Next, use your goblin racial--did I mention that you're a goblin engineer?--to gain lateral movement. Disengage might also work (untested) but I assume it would be hard to have a target anyway. So--up, up and over.
Possible uses are many.
- Reach high ledges in instances to evade out adds, or heal/dps while evading game mechanics and AoEs. Generally speaking, being high up in a boss fight is often advantageous.
- Hide the flag in unreachable places in pvp, or possibly just rocket up to the roof in WSG from inside the flagroom.
- Skip large parts of instances. Remember all the TBC instances with backdoors that were made "one way" via a short cliff drop? Also the backdoor of deadmines, getting onto the roof to skip a large part of SFK, etc.
- Exploration
Nitro Boosts: Nitro Boosts - Spell - World of Warcraft
Rocket Jump: Rocket Jump - Spell - World of Warcraft
If your boosts don't backfire the first time, swap your belt out for a different one and it resets the cooldown to the 30 second item change. Minor exploit on its own.
Using the goblin rocket jump puts a cooldown on slowfall, but (THEORY) if someone was able to find a slowfall effect that it didn't cancel, you could also use this to fly a really, really far distance. Lot of unusual slowfalls out there--the holiday beer, the lowbie warrior shield, the parachute from the quest in feralas, noggenfogger.. Which is also useful.