Activate Shilgengar by sacrificing Threefold Thunderhulk.
When Threefold Thunderhulk dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to its replacement effect.
When Threefold Thunderhulk enters, it triggers, creating a number of 1/1 Golem artifact creature tokens equal to its power.