Driver for 4S lion and 6V/12V Cree XHP50.2

Could you someone recommend me buck driver for 4 lions aku in series (12-16.8V) and Cree XHP50.2 in 6V version (prefered) or 12V version?
With 3 mod configuration cca 3A, 1,5A and 0.7A?

Will be used as replacement for MC-E in older diving flash light.