Activate Krark-Clan Ironworks by sacrificing Triplicate Titan, adding CC.
Triplicate Titan dies, triggering itself and Nim Deathmantle.
Resolve the Triplicate Titan trigger, creating three 3/3 Golem artifact creature tokens.
Activate Krark-Clan Ironworks by sacrificing a Golem, adding CC.
Resolve the Nim Deathmantle trigger from step 2, causing you to pay 4 to return Triplicate Titan from your graveyard to the battlefield, and attach Nim Deathmantle to it.