It seems that Warhammer: Age of Sigmar fans won't have to wait too long to see how things will be changing thanks to the latest announcement by Games Workshop.
On their Warhammer Community page, Games Workshop discussed that the Dominion box, which would include the first printing of Age of Sigmar's brand new third edition Core Rules, would be available for pre-order on Saturday, June 19th. However, in the exact same paragraph, Games Workshop revealed that anyone can download this sought-after core rulebook right now on their website, for free, in order to get a look at how things have changed.
The post goes on stating, "Over the last couple of weeks, we’ve been explaining some important rules updates in the new edition, but today the whole system is yours to download and browse at leisure. The beautiful 360-page full rulebook you get inside Dominion will feature so much more of course, but getting familiar with the essentials of the new edition will help you prepare for the big changes about to affect your games."

Basically, the free version of the rules is for just that: basic rules. These include things such as Endless Spells now being moved at the end of each and every hero phase, making them much more mobile than before, allowing players to set up elaborate traps and ambushes. There is also a greater focus on Hero and Monster units which include brand new battlefield changing abilities called Heroic Actions and Monstrous Rampages respectively. Finally, there is a greater focus on command abilities and command points, which greatly reduce downtime between fights and keep things straightforward and kinetic.
If you want more specific rules changes for certain armies and factions, you will have to spring for the book included in the Dominion box, which we previewed here.
All in all, it's not a bad way to promote the new edition of Age of Sigmar. It helps give players time to learn and adjust to the new rules and get a better understanding for how it will change their games going forward just in time for the more specialized rule changes for their army of choice to come around.
If you want to try these rules out yourself, you just have to click here and specify your language of choice.