Shroud of the Avatar's combat system. That is, it's time to actually have access to the skills that will eventually be in the game. Release 5 is now open to the game's backers, and it brings with it 35 of the 171 skills that will eventually be in the full game. Some skill lines are more fleshed out than others; while the Death line has access to death in both touch and ray form, Water is currently limited to Ice Fist and nothing else. But that will change.
Aside from this major addition, the new release will also see the first wave of potential backers admitted into testing with keys that have been given out via an Alienware Arena promotion. There's also a new lighting model in place and a variety of functionality updates. Whether you're in the early access period or just want to keep an eye on the development, check out the full list of Release 5 notes for more details.