The E99 Bomb is a device in Singularity.
The E99 Bomb was the Soviet Unions answer to the threat of America's Atomic Bomb and utilized the power of E99 instead of more typical nuclear isotopes, resulting in a far more powerful bomb. In the alternative timeline created by Nathaniel Renko saving Viktor Barisov it was revealed that a E99 Bomb was used to destroy the Eastern coast of the United States of America in a preemptive strike, most likely resulting in their surrender.
One of the first produced models of the E99 Bomb can be found within the cargo hold of The Pearl. Renko is tasked with recovering this bomb and later charging it at the E99 Rector in order to use it to destroy The Singularity and restore the timeline. After destroying The Singularity, it is revealed that in the current timeline the explosion of the reactor is what caused the accident of Katorga-12, and that Nikolai Demichev simply rebuilt it.