Exotic Quest: A Light in the Dark (Thorn)

Follow these step-by-step to complete this quest:
 * 1) Complete the Summoning Pits strike on the Moon
 * 2) Earn 500 points by killing Hive on the Moon
 * 3) Earn 500 points in the Crucible
 * 4) Use one mote of light to buy an Infusion of Light from the Speaker
 * 5) Kill Xyor the Unwed on a special level 26 version of the Summoning Pits
 * 6) Return to the Speaker to claim your reward