While most other cards on this list have a rather widespread support throughout formats, it looks like the new Ashiok Planeswalker has only one viable application: Blue-Black Control decks in Standard and Pioneer.
This color pair is not as strong in Modern, where blue-white decks fill in the niche pretty nicely. But Standard and Pioneer can really make this work in the best way possible, including Grixis lists.
The current price for Ashiok is about right, and there should be no drastic movements on the market. If you feel like playing it, then this is a good time to grab a playset. But if you want to invest, then be more patient.