even though they are new traps they work the same as any other trap in zombies, you buy the trap to activate it and than it will kill zombies. They also added in two new types of traps that are pretty handy to use, there is the acid trap and the fan trap. Hell’s retriever is just the name of a new weapon that is the flaming tomahawk, and when you make the tomahawk blue it than becomes the hell’s redeemer. They also have some new items in Mob of the Dead which includes the hell’s retriever which can turn into hell’s redeemer.