From Halopedia, the Halo wiki
The GBU-1105 bomb, nicknamed the "cryo bomb", is an air-dropped weapon in service with the UNSC Armed Forces. It makes use of an unconventional payload that when released is capable of freezing a small area and doing great damage to personnel and equipment in its blast radius. It is typically dropped by a B-65 Shortsword bomber.
The cryo bomb can freeze even Type-47B Scarabs in their tracks and severely weakens their armor, allowing them to be shattered. Although the cryo bomb may freeze ground units, its best effect is that most air units caught in the blast will freeze and crash into the ground instantly; however, a UNSC AC-220 Vulture can maintain flight but will stay low to the ground until the effect wears off, unless it has taken sufficient damage prior to the cryo bomb's impact, in which case it will be destroyed.
If a production building like a Barracks or Supply Pad is caught within the cryo bomb's range, the building will cease production for the period of time, or in the Supply Pad's case, incoming supplies will stop. It can be requested only if Ellen Anders is the selected hero unit. The cryo bomb can be enhanced three times from the Field Armory to make its effect last longer and to increase the number of air units capable of being destroyed. The cryo bomb is best used when a player wants to freeze their opponent's aircraft and uber units. This leader power must be backed up with troops because unless the units are heavily damaged, this attack will not kill them. In campaign mode along with working well against Covenant air units, its highly effective against the Flood too. While a cryo bomb won't kill them, it freezes the Flood in place, opening them up to a brief unimpeded attack before they unfreeze.
Halo Wars 2
In Halo Wars 2 the cryo bomb is a leader power exclusive to Serina. Like its Halo Wars counterpart the cryo bomb has three upgrades and does not kill units. Unlike its Halo Wars counterpart it will not cause aircraft to shatter. Instead players must cause extra damage before the enemy unit will shatter.
List of appearances