Ask and ye shall receive!
BD has max 29 Armour, 21 Life. So 50 before bonuses. We have what? 26 kingdoms currently? 4 are magic, 8 are attack I think. So 14 kingdoms are life or armour. Assume all are maxed and all are at double skill bonus, meaning another 28 points on top of the 50, bringing us to 78. Throw a couple guild bonuses on to bring us to an even 90 effective health. If we assume 1 BD in each PVP team, and say... 100 PVP matches a week? (pulling a number out of the air here). So 100 BDs a week at 90 EH each, so 9000 EH per week. Say for examples' sake we have 100,000 souls stashed, Pharos-Ra does 1 extra damage for each soul, meaning he hits for [Magic(8) + 1] + 8 from double kingdoms + 2 from guild, so 19 damage plus souls, so 100,019 damage per cast. So each cast would knock out 11 weeks worth of BDs, or basically 3 months.