X:\Dev\Minecraft\forge-1.10.2-12.18.2.2099-mdk>gradlew setupdecompworkspace --offline
This mapping 'snapshot_20160518' was designed for MC 1.9.4! Use at your own peril.
#################################################
         ForgeGradle 2.2-SNAPSHOT-c438b06
  https://github.com/MinecraftForge/ForgeGradle
#################################################
               Powered by MCP unknown
             http://modcoderpack.com
         by: Searge, ProfMobius, Fesh0r,
         R4wk, ZeuX, IngisKahn, bspkrs
#################################################
:deobfCompileDummyTask
:deobfProvidedDummyTask
:getVersionJson
:extractUserdev

FAILURE: Build failed with an exception.

* What went wrong:
Could not resolve all dependencies for configuration ':forgeGradleUserDevPackage'.
> Could not resolve net.minecraftforge:forge:1.10.2-12.18.2.2099.
  Required by:
      com.yourname.modid:forge-1.10.2-12.18.2.2099-mdk:1.0
   > No cached version of net.minecraftforge:forge:1.10.2-12.18.2.2099 available for offline mode.
   > No cached version of net.minecraftforge:forge:1.10.2-12.18.2.2099 available for offline mode.
   > No cached version of net.minecraftforge:forge:1.10.2-12.18.2.2099 available for offline mode.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Total time: 9.015 secs