Tanks are nowhere near invincible Rpg to engine block Aircraft armament (main guns, no missiles, no bombs) Shaped charge of high explosive material to blow off inside spaulders and rivets, tearing crew to shreds. (Key word is shaped. Battlefields unshaped block of c-4 would do very little) AT mine to immobilize tank and cause concussion damage to undercarraige severe enough to kill crew Molotov cocktail to burn through wires and overheat/damage engine block AT cannons Schwerer Gustav Just to name a few things to destroy a tank.