Forge version: MDK 1.12.2 - 14.23.1.2578
Botania version: r1.10-352-deobf
Link to crash log: https://gist.github.com/TurboPig/103e65edb1997bed3b3aceaa95eb71c4#file-crash-2018-01-06_14-54-20-client-txt

Steps to reproduce:

1. Add deObf Botania JAR to /libs folder.

   • I have also put compile files("libs/Botania r1.10-352-deobf.jar") in build.gradle dependencies; same error regardless.

2. Attempt to run client

What I expected to happen:
Botania should be added to the dev environment.

What happened instead:
Crash!

As per issue #2378 I have also attempted to delete the /build folder, run setupDecompWorkspace again, and refresh the Gradle project, but this has not resolved the issue.
Additionally, trying to download Botania through the Gradle dependencies (how do I word this? Adding the Botania repository and specifying the dependency as the appropriate path) results in a handshake error. Disabling SNI only resulted in further errors. Thus, I have instead added Botania to the /libs folder.

add this line to your gradle: https://github.com/Vazkii/Botania/blob/master/build.gradle#L57

Unfortunately, useDepAts = true made no difference. I am still getting the same crash.

Yeah, this is not solved. You can do a "patch" by copying botania_at.cfg to your build/depAts folder, but this is NOT A SOLUTION, merely a way to get around the error for now.