Which derailler hanger?
These claim to fit the Saracen Raw 2, which appears to be the same frame with slightly different components. It looks right based on what I can find on the internet. 

The compatibility of a hanger is between it and the frame, in general, standard rear derailleurs are compatible with all hangers.

https://www.ebay.co.uk/itm/SARACEN-Mantra-Raw-2-MONGOOSE-Tyax-Comp-Super-Rear-Gear-Mech-Hanger-CC003-/301758510575