It is a matter of fact that the Bronze Dragons are the coolest dragons. Their domain is over time, and that means they are dealing with the most potentially dangerous domain of any of the dragonflights. While Nozdormu is the Aspect, still alive at our point in time (or arguably alive, corrupted, and dead simultaneously at all points in time, because time travel is insane,) the one we tend to interact with the most is Chromie, also known as Chronormu (it's unclear whether Chromie is a male dragon, given the name, that just prefers to take the form of a female gnome, or a female dragon who has a masculine name, or maybe we don't have their naming conventions down, or that maybe Bronze Dragons don't get hung up on the whole gender issue.)
The Deaths of Chromie scenario is a new feature with 7.2.5 that players can repeat as often as they like, and appears to be an "evergreen" feature that scales the player to an appropriate level and item level (112 and 1000, respectively.)
Chromie realizes that at some point in her future, she's going to be killed, and so she enlists your aid to travel to that future and try to prevent her death. Shortly into your time-travel excursion, you discover that there are actually eight threats to her, all of which will be lethal. On top of that, the earliest she can get you to before her deaths is fifteen minutes, due to some mysterious interference (calling it now: Infinite Dragonflight.)
However, you can repeat those fifteen minutes as often as you like, and in fact, you benefit a lot from knowing what's coming. For instance, there is a boss in each of the dragonshrines that requires a short series of quests to reveal, but in subsequent trips, you can simply go right to the boss and fight it. Each of these bosses drops an item that will unlock a different area: the Battle of Andorhal (circa Cataclysm,) the Culling of Stratholme, the Well of Eternity, and another era I don't remember right now.
These segments appear to be less fast-forward-able, though there do seem to be some benefits to having done them before. In the Culling of Stratholme, you need to get a key to town hall to get to its boss, and to do so you need to complete a series of quests where you buy a bunch of things from vendors. Once you've done those quests once, though, the quest items become available before you get the quests, so you can simply run to each shop and buy everything in one trip and then toss them to the two NPCs that request them right as they do.
Killing things in the scenario will upgrade your reputation with Chromie, and at each level you will be able to give her a new talent (which works a bit like class hall research.) The first two can be switched quickly at the start of each run of the scenario, but later ones require research time. However, you can continue earning reputation of the next level even if there's no talent selected, so it's not as bad as the class hall stuff.
I'm really just scratching the surface here, as there are plenty of items and buffs to get, as well as rewards including bronze-dragon-themed transmog (for successfully preventing all 8 attacks within the time limit,) as well as pets and the Time Lord title for filling one's reputation with Chromie (I must have it!)