The SU-152 "Zveroboy" (СУ-152) was a Soviet self-propelled heavy howitzer used during World War II.It mounted a 152 mm ML-20S howitzer with a PT-5 gunsight on the chassis of a KV-1S heavy tank. Later production used IS tank chassis and was re-designated as ISU-152. Because of its adopted role of as an impromptu heavy tank destroyer, capable of knocking out the heaviest German armoured vehicles Tiger and Panther tanks, as well as the Elefant tank destroyers - it was nicknamed Zveroboy, "beast killer".
The SU-152 in FHSW has like the real tank two purposes, load the APHE shells to play the tank killer or HE to clear infantry nests. With the HE rounds you can also penetrate walls to kill hiding infantry, use this to your advantage. In tank combat take into account that the reload time is pretty high so you have to be very accurate with your shots. Otherwise you'll give away your position and your enemy can kill you before you get your second shot off.
The heavy shells drop down really fast so it takes some practice to shoot accurate over great distances.