RECENT XMM-NEWTON OBSERVATIONS OF THE TIDAL DISRUPTION EVENT ASASSN-14LI HAVE REVEALED VARIABLE BLUE-SHIFTED X-RAY ABSORPTION LINES CONSISTENT WITH A SUPER-EDDINGTON DISK WIND OR ORBITING GAS IN A NEWLY FORMING ACCRETION DISK. THIS ADVANCE MAKES IT POSSIBLE TO TEST A BROAD ARRAY OF PREDICTIONS FOR HOW ACCRETION FLOWS WILL FORM AND EVOLVE IN TDES. THE CAPABILITIES OF THE RGS ARE IDEALLY SUITED TO TAPPING THIS DISCOVERY SPACE. WE REQUEST A 100 KS (SINGLE-ORBIT) TOO OBSERVATION OF A BRIGHT TDE IN CYCLE 15. NEW OBSERVATIONS CAN VERIFY AND SHARPEN THE RESULTS FROM ASASSN-14LI AND TEST THE NATURE OF POST-DISRUPTION ACCRETION.