To play Wrath tonight you'll need to update the game. The game installs version 3.0.1 when you upgrade to Wrath, and you'll need to update it version to 3.0.3. That means installing the following two patches:
- Version 3.0.1 - > Version 3.0.2
- Version 3.0.2 -> Version 3.0.3
Note: If you saved the files from previous patches, you're all set. But be sure they work and are fully saved before you go out and get Wrath tonight – no need to waste time downloading stuff again.