1Activate Scaretiller by tapping it, targeting Cacophodon.
2Scaretiller triggers, returning Riveteers Overlook from your graveyard to the battlefield tapped.
3Riveteers Overlook enters the battlefield, triggering itself and Roaring Earth.
4Resolve the Roaring Earth trigger, putting a +1/+1 counter on Cacophodon.
5Resolve the Riveteers Overlook trigger, causing you to sacrifice it and search your library for a basic Mountain, Swamp or Forest and put it onto the battlefield tapped.
6If you put a land onto the battlefield this way, Roaring Earth triggers, putting a +1/+1 counter on a creature you control.
7Resolve the Scaretiller ability from step 1, dealing 1 damage to Cacophodon.