Microsoft and Qualcomm have apparently worked together for a long time in order to ensure that the Adreno GPU in the chipsets fully supports the DirectX API collection. DirectX 12 greatly increases the looks of the games you play on WP devices by boosting performance – it uses the cores of the CPU and the GPU even more efficiently. At the same time, the power consumption is also reduced and the games will drain significantly less of your smartphone's battery.
However, DirectX 12 won't land on WP devices anytime soon, as it is expected to arrive in the end of 2015. At the moment, the current version of Microsoft's mobile platform supports a modified version of DirectX 11, which uses Direct3D with a feature level set to “9_3”. This means that Windows Phone games can't benefit from most of the nifty functionalities of DirectX 11 – they can only make use of the features that DirectX 9.3 is toting.
Thanks, anonymous tipster!
source: G for Games, Microsoft