No, 300k will be burnt not from circulation supply but from rest 3m of total supply https://coinmarketcap.com/currencies/luxcoin/, which mean from premine.
OK,
to 900000 you will add 300000 now imagine how exchange rate will drop
i think 15th rate will be about ~0.00150 or even lower depends on market panic at this coin
I think "burn" means reducing supply - i.e. the "out of circulation" supply will be reduced from 3 mln coins to (3 mln * 90%) 2,7 mln. It should have a slight positive impact on the exchange rate.
Is it correct?