This actually raises a question about the nails. Does each nail killed shave off a percentage of damage, or is it 4+ nails is 9999 damage?

In the case of the first, you can take out four nails out of 8 and it would only drop damage to the 4999 range. In the latter case, you would need to destroy X number of nails until the end result was 3 or less or else get one shot anyways.