You have The Mouth of Sauron but need support.
Look for Dunland Crebain or Claim the Precious.
Defense before the expensive reward. Milling a few cards is usually setup, not a plan to empty their entire library.
You already have Dunland Crebain.
Consider The Mouth of Sauron if it fills a useful job.
Crebain supplies a flyer and an Army. The Mouth then adds counters to that Army based on the opponent’s instants and sorceries in their graveyard.
The support is missing
Take castable creatures and answers. If the engine never arrives, use the good cards rather than forcing narrow support.