Heart of the Reich takes place at the final battle of Berlin. Dimitri, Reznov, and other Soviet troops charge through Berlin toward the Reichstag, a building used for German politics where all the remaining Germans are making their last stand. You start the mission by being carried out of a metro by half-drowned Reznov, who is once again praising you for cheating death once more. Reznov is infuriated by Chernov's lack of brutality towards the German forces, and grants him the task of placing the Red Army flag upon the high balcony of the Reichstag claiming victory for mother Russia. When starting the mission, trade your SVT-40 for the FG42 lain along the boxes. You first assault a building where Germans are holding out. Use your starting weapon, a PPSh-41or FG42 to mow down any Germans inside. You can also just walk around this building and kill all nazi's from behind. Once you break through the building, head into the adjacent Library and kill any defending Germans. Then jump out of an open window to find a trench and walk along it. Once inside, of the partial underground building ahead, Reznov will give a short speech, before a whistle is blown, and then charge forward with your comrades, but with great care, as you will take heavy fire on the Hardened or Veteran difficulties. Taking cover and tossing grenades at Germans behind cover is recommended. You must destroy the four Flak 88s by going right up to them and planting the charges but a Panzerschreck is also available by a destroyed T-34. Throwing grenades at the 88s beforehand to clear out nearby soldiers is ideal, as well as Molotov Cocktails. Once you destroy the 88s, move forward to the steps of a large building, known as the Reichstag. Kill any Nazis heading towards you.
Tread carefully, as on the high balcony are Germans wielding Panzerschrecks. On Veteran mode it is nearly impossible to go up the stairs without eliminating the Panzerschreks in the top windows of the Reichstag. Move up the ladder in the building in front of the stairs and pick up the PTRS-41 sniper rifle up there. Go to a suitable sniping position and keep taking out the panzershrecks in the windows. Doing this 5-6 times will ensure they never respawn and going up the staircase will be very easy, even on veteran. You will find an FG42, and Panzerschreck in the shelled building to the left. Afterward, move up to the front of the Reichstag and a falling column will crush the barricade but be careful not to stand in the way of the falling column. As you move up, a hiding flamethrower-wielding German will ambush Chernov and blast him with his flamethrower. Reznov comforts his dying friend and takes his diary, saying that "someone should read this". As you enter the Reichstag, the mission will finish.