Arborea: Corruption Adds more depth without more complexity into one of my top100 games!

About Arborea: Corruption, from BoardGameGeek:

The sky dims over Arborea's prospering ecosystem as something blighted creeps across the lands. Darkness spews forth from an ancient city, corrupting everything it touches. Can your villagers work together to hold back the decay, or will this be the end of the current cycle of Arborea? In Arborea Corruption send workers down new tracks to remove corruption from your creatures and ecosystems, Make offerings to the new ‘Portal Sage, gain additional rewards for clearing corruption from the shared sages, and collect unique and ancient ‘Majestic Creatures' to bring into your ecosystems Arborea Corruption is an expansion for the hugely popular Arborea game, in Alley Cat Games' advanced games line