I was searching for a guide with store codes to redeem and found none, so ill try to make a list here, theorycraft is posting a new one everyday on twiter, but there are some stray codes around the web. help me expand it in the comments!
You can find the redeem tab on Store>Redeem
As of 26/07 18:23GMT

BIGCAPSULE > Armory capsule

xPetuSUPERVIVE >Shiv's agent skin (i think all streamers codes are for this same skin, not sure)

THANKYOU > Armory capsule

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No longer active codes:

LAUNCH > Armory capsule


Ill try to update the list everyday, puting now ones first on the list.