obtain tc through game sell tc for usd buy qi for usd there you go you just got qi for tc
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a tc to qi conversion sink (that is somewhat reasonable) might be okay, but trading qi between accounts without admin intervention and such is just straight up not gonna happen, too many malicious possibilities for that to be a good idea. qi is essentially your account's "rank", being able to trade rank as if it were a currency is pretty ludicrous.

qi to tc probably wouldnt hurt but that would so not be worth it anyway lol
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its also not gonna happen cuz nabi want ur cash brudda