All service games will come to an end eventually. Duelyst, the free-to-play TCG/strategy hybrid will be shutting down its servers on February 27th, permanently.
The announcement on the Steam page has revealed that players are no longer able to pay for diamonds (premium currency), and will be offering refunds for those that purchased some between December 21st,2019 to January 24th, 2020. For players who still have diamonds, developers Counterplay Games are reducing costs of diamond purchases by 99%- buying 50 orbs (card packs) now cost 60 diamonds instead of 6000.
Dueyst looked promising when it launched in 2016, but it looks like it may have not enough players, or making enough money to justify continued operation. At least the good news is we already know that these developers have another game coming. They are making waves with Godfall, the looter-slasher action game that is the first game announced coming to PS5.
Source: Steam