The key card is present but its support is thin.
Prioritize useful support such as Thawbringer or Scrounge for Eternity.
Broodtender can sacrifice itself to return any creature or Spacecraft, including Pinnacle Kill-Ship. Scrounge is a separate cheaper option only for targets with mana value five or less.
Your deck already enables the plan but is losing the early turns.
Take a castable early creature or efficient answer before a second expensive payoff.
Scrounge cannot return Pinnacle Kill-Ship or the creature sacrificed to pay for Scrounge. Its target must already exist in the graveyard when targets are chosen.
The support is missing
Favor independently useful creatures and interaction if the narrow support does not arrive.