EBuild is a new cross-platform build tool chain that we are switching over to for Elements 10. Eventually, EBuild (and with it large portions of the Elements-specific tasks and tool chain) will be open-source and available on GitHub.
Ebuild replaces our use of MSBuild and xbuild within Fire, Water and Visual Studio, and allows us to be much more flexible and innovative with our build process. It is already the default build chain for everything except when building .NET projects in Visual Studio.
Fire and Water also use EBuild internally not just for the build process itself, but also for resolving references inside the IDE. This is most notable with the advanced display and handling of Gradle and NuGet package references.
You can read a lot more about EBuild in its Documentation section.