I've been buying exotic engrams from Xur since the new expansion was released to get a good Warlock helm like Skull of Ahamkara, The Ram, or Obsidian Mind. I've bought 4 so far and got 2 Titan helms (Saint-14 and Skullfort) and 2 Hunter helms (Symbiote and Third Man). I only have about enough motes of light for 1 more engram this week, so I hope Rahool is in the Christmas spirt :)
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I don't think the Ram is released yet, thought it was a House of Wolves Exotic.