I decided to make it an elite heavy/medium cruiser (depending on the era) with an emphasis on speed and stealth. I try to incorporate less frequently used gear on my ships so the KWF-1 engine (only used in one ship in the official Recognition Manual) seemed like a good choice along with a 2/3 ratio shield generator for the earlier versions. Debuting not long before the first Romulan/Klingon technology transfer, the D-15 Quick Death cruiser class incorporated and pioneered the use of torpedoes and cloaking technology in the Klingon Empire. The B variant is identical to the A except that it adds 2 superstructure and the RPL-1 plasma torpedo and KCC cloaking device. While quickly overshadowed by later D-7 and D-10 upgrades, it got a significant upgrade a decade later which put it midway between the aforementioned ships in terms of total firepower. With the subsequent C variant, I decided to break with the mould of a single forward photon torpedo launcher and use a dual magazine but single launch tube torpedo on the command pod for some more focused firepower along with higher numbers of medium (instead of heavy) disruptors as well.
For a full size version of the jpeg version of the sheet, just right click and open it in a new window. The pdf is available for free download at the link above as well. Special thanks to Crypic Studios for coming up with some cool Trek ships designs for STO and to fasaststcs.com for the sheet template I use. As always, feel free to comment below and let me know if you find any typos or errors that I missed and I hope you enjoy it!