The phrase "instrumental role" refers to somebody or something playing a vital and important part in achieving a particular goal or outcome. Full definition
Fortunately, I am working with a strong team of talented colleagues who have all played instrumental roles in addressing each of these areas. (gse.harvard.edu)
It's good if you have held only a few positions, but held an active and instrumental role within them. (job-interview-site.com)
Rubin played instrumental roles in state and federal recovery projects related to the damage wrought by storms Sandy, Irene and Lee. (timesunion.com)