The key card is present but its support is thin.
Prioritize useful support such as Brambleback Brute or Reluctant Dounguard.
Elder Auntie and its token remove both counters from Dounguard. Later Hurler can give a restored attacker flying before combat.
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.
Hurler can only give another creature flying. Budget its activation before spending all your mana on a new spell.
The support is missing
Favor independently useful creatures and interaction if the narrow support does not arrive.