Sample date 15 October to 1 November, which just happens to correspond to that used in the e-mail from Scott's Cheap Flights today!
Even if you can't travel on the rare days the flights are at their cheapest, you could achieve similar prices building this trip yourself in separate legs since AirAsia has a sale on. The deals are mostly around October/November but you get many more options in September doing it yourself (and sleeping in KL each way).
This isn't so much an amazing deal as it is an announcement for long-time travelers to Asia. It's only since late last year you could fly directly from Kuala Lumpur to Luang Prabang or vice versa on any airline. Laos might feel less "exotic" now that it's so accessible.
This deal was received in the free subscription to https://scottscheapflights.com/
P.S. Melbourne and Gold Coast don't have bad prices either and of course Perth as always.
EDIT: Still showing from $376 with Google Flights via Air Asia Direct
For anyone who hasn't been there yet, it's an interesting laid back country with plenty in the way of jungles, animal stuff (elephants etc), or just chilling in the towns if you want. Not quite as cheap as Thailand, maybe due to the bad roads and the currency being unwanted by any other country.
I've been there twice, and if I hadn't come back from Asia last weekend I'd easily book this.
Normally a flight in to Laos from Thailand is $160 USD on the terrible Laos Airways, or you take a death defying bus from hell for about 16 hours over the border. This is THE way to go there, even if you fly back home from Thailand/Vietnam/Cambodia.
There are already a few tourists there, so if you grab one of these flights, you'll see it before they swamp the place too badly in a few years.
Some people like me who love Thailand are a bit over the hordes of tourists there, so places like Laos and Myanmar may take off a bit more,