Scala is a modern, high-level, multi-paradigm programming language that seamlessly integrates features of both object-oriented and functional programming. Built on the robust and highly secure platform of Java Virtual Machine (JVM), Scala enhances productivity by providing a concise and type-safe way to write general-purpose software. This makes it significantly valuable and sought-after among tech companies in diverse industries ranging from finance to software development, from healthcare to gaming. Mastery of Scala is often required or preferred for roles such as software developer, data engineer, and back-end developer.

Scala offers several significant advantages over traditional programming languages. It allows for more concise code, thanks to its expressive syntax. It offers high-level abstractions that simplify complex coding tasks, and its static types help avoid bugs in complex applications. It is also popular for its inherent ability to scale, which is partly why Twitter and several other high-traffic websites use it.

For learning or mastering the Scala language, a solid foundation in Java or any other object-oriented programming language will be hugely beneficial. Since Scala is designed to interoperate seamlessly with Java and runs on JVM, familiarity with Java often allows developers to understand Scala more intuitively and leverage existing Java libraries and frameworks effectively.

However, given that Scala also incorporates functional programming principles, understanding functional programming concepts like immutability, first-class functions, and lambda expressions would be extremely useful.

Other valuable auxiliary skills in the Scala ecosystem may include familiarity with build tools like SBT or Maven, knowledge of Scala testing frameworks like ScalaTest or Specs2, and experience with reactive programming libraries like Akka and Play Framework.

The versatility of Scala and its growing adoption by tech industries worldwide make it a valuable addition to a candidate's tech skill set, potentially opening up expansive career opportunities and positions.