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In solar-type stars comma rotational shear at the tachocline is thought to power a dynamo comma generating a magnetic field that heats the star.s corona comma which produces X-rays. X-ray flux and rotation rates measurements therefore provide insight into the strength of the underlying magnetic field and its dependence on rotation. But this rotation-activity relation remains unconstrained for the slowest rotators openPari.e. comma Rossby number > 0.8closePar. We propose to observe six 700-Myr-old solar-type slowly rotating Praesepe stars comma for a total of 157 ks of exposure with the EPIC camera. Our data will provide invaluable information on the rotation-activity relation for the slow rotators comma enabling tests of dynamo theory in a largely unconstrained regime.