I believe you are same person who posted a question yesterday on Accenture skills interview :). If you are, then congrats on making it through to next stage..that was quick I must say..

For STA, most important thing is to clarify the format with HR. Accenture experiments with this and in the past year, I came across 2-3 different styles. Based on my experience coaching candidates, it could be:

• Discussion based case/candidate led case
• Big thinking/Open ended case or series of questions
• Or you might be given Accenture's strategic pillars and asked to create a small pitch or even a small case and given some time to prepare a presentation/pitch

Please clarify with the recruiter/HR as there is risk you could be misled by generic advice on this forum. 

If you need help preparing, feel free to write to me directly.