A fork of Rural Dictionary
'No cost too great' is an iconic and recurring line said by the Pale King from the game Hollow Knight. It is often humorously used in situations where a person does something that is too much work, just to reach their goal, e.g. sacrificing thousands of your children just to chain and lock one for years to contain a moth God.
Person 1: "YOUR HIGHNESS, ISN'T THIS A BIT TOO MUCH?"
Person 2: "No cost too great."
Person 1: "SIRE, YOUR CHILD IS BURNING!"