Based on the SU-85 which was made superfulous after the introduction of the T-34/85 which mounted the same gun on the same chassis in a revolving turret. Since the chassis could handle a bigger gun in a fixed mount the SU-85 was upgunned with the 100mm. Armor wasn't too impressive by German TD standards but the gun was one of the best AT guns of the war capable of penetrating more armor than even the 122mm on the IS tanks. It's service life went well beyond the end of WWII and some countries still use it even to this day.
This is the tier VIII Russian TD. It is pretty quick though armor doesn't stack up to other TD's at its tier. It has a very quick fire rate though which leads to a good damage per minute. Avoid taking shots and play the support role like most fixed TD's.