There's a new guy in the tower by the crucible vendors, his same is "Agent of the nine" and for 23 motes of light he will trade you an exotic engram. Maybe everyone already knows this but I didn't so I wanted to help avoid other people waste their motes of light on emblems and the likes. He will also trade you strange coins for exotic gear but the stocks refresh every so often.
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OP is correct ( even if he is trolling) you should save your motes, save them until house of wolves comes out so that you can have a better chance of a "new" exotic with (42 light?) it will increase your chances of reaching level (34?) faster...