This is a utility class of the EnhancedItems package by Wormbo.
It will be spawned automatically by Legacy:EnhancedItems/EnhancedMutators and Legacy:EnhancedItems/EnhancedWeapons to handle the extended death messages offered by several EnhancedItems classes. The mutator will automatically register itself as a message mutator and doesn't have to be registered in the general linked list of mutators.
It creates a SpawnNotify (the EIDeathMessageSpawnNotify) serversidely, which automatically registers the EIDeathMessageMutator with all Legacy:EnhancedItems/EnhancedMutators, Legacy:EnhancedItems/EnhancedWeapons, Legacy:EnhancedItems/EnhancedProjectiles, Legacy:EnhancedItems/EnhancedAmmos, Legacy:EnhancedItems/PickupPluses and Legacy:EnhancedItems/EIEffects so those can use their SetKillType() and RestoreKillType() functions.
- WhoPushedMe (the Who Pushed Me? mutator)