Masquerade is Substratum's background service that runs functions that should run on a completely separate thread. This alleviates the stress on the main app and allows for Substratum to run more smoothly.
If you are a ROM developer, by now you should know how to track new packages while building your ROM. However, if you don't - please follow these steps:
Add "masquerade" under PRODUCT_PACKAGES in "vendor/config/common.mk"
PRODUCT_PACKAGES += \
...\
...\
...\
masquerade
Add the project path in "platform_manifest/default.xml"
<project path="packages/apps/masquerade" name="substratum/masquerade" remote="github" revision="n-rootless" />
platform_manifest/default.xml: https://github.com/TipsyOs/platform_manifest/commit/fbff9ea598ec04f4f4a69687a8024770fefa83de
vendor_tipsy/config/common.mk: https://github.com/TipsyOs/vendor_tipsy/commit/2e72dc4eb3a206fad34e9c4f130e270180eab1c2