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If you like owning Destiny on disc ... (Destiny)
and want the new box of the legendary edition, Gamestop is offering $20 off the Taken King disc for a trade-in.
http://www.gamestop.com/collection/destiny-the-taken-king?cid=rtg_10000277
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I have poor reading comprehension
EDIT: Somehow I misread the OP as saying TTK was only $20 if you traded in, but he correctly said they're giving you $20 off. My bad.
They're giving you a $20 credit towards the legendary edition (regularly $60) when you trade in the original Destiny disc. Which makes TTK $40 for you. BUT this is still probably a good idea for disc people because TTK legendary edition is then (a) the same price as normal TTK AND you will be able to play with just the new disc in your system.
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I have poor reading comprehension
They're giving you a $20 credit towards the legendary edition (regularly $60) when you trade in the original Destiny disc. Which makes TTK $40 for you. BUT this is still probably a good idea for disc people because TTK legendary edition is then (a) the same price as normal TTK AND you will be able to play with just the new disc in your system.
For the disc part you still will only have to have the original Destiny disc in your system no matter what. The Legendary and Collector's editions just come with a code for all the DLC (there is a Bungie help article about it, and it's confirmed by a handful of people who have received their Legendary editions already).
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I have poor reading comprehension
Yep. This is basically a way to get the new box art.
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I have poor reading comprehension
Is that a thing that people care about?