TOS-1A and TOS-2. Thermobaric “God of War”

Since the beginning of the invasion of Ukraine, the Russians have been utilizing many types of rocket artillery. 1 of the most dangerous types for Ukrainian soldiers is the 1 utilizing 220 mm thermobaric missiles, i.e. the tracked multi-guide rocket launcher TOS-1A and the lighter wheeled TOS-2. What are these structures and why is the rocket ammunition utilized by them so dangerous?