When you want to accelerate the budget, if you don't aim a cost per action, you can remove target CPA. This way, Marvin will spend the daily budget which had assigned to him.
If you'd like to control the CPA, then you can increase the cost amount to the maximum level that you can afford. In this case, when Marvin reaches to the given target cost, he will spend as much as he can.
We don't guarantee that Marvin will spend the whole budget. In this kind of campaigns, the priority target of the Marvin is to reaching the CPA.