Looming hell costs exactly 150 blood slaves, and it is a global EVERYBODY HATE, exactly like astral corruption. So, you aren't supposed to cast them when you reach the exact amount. As in many MP games the players will gather together the pearls for a very good Dispel, you need to pump in it AT LEAST 100 more slaves to make it very difficult to dispel - it will usually take you just one more turn of blood hunting.
thejeff is right, the dispelling mechanics are difficult but you can search the manual, the FAQ and a previous thread for them. Anyway they surely consider the path level of the caster and MAINLY the gems/pearls/slaves the caster of the global put IN SURPLUS of the initial cost in the global itself, compared to the pearls the dispeller puts IN SURPLUS to the dispel.
If I understood correctly, you put exactly the 150 slaves for the Looming Hell in your global, and he pumped in it 71 more pearls to be sure to dispel it. At this ratio, the dispel was obvious, but if it can comfort you somehow he quite wasted those 71 gems in surplus as putting just 10 in the dispel would have made it a quite sure dispelling too
P.S. damn, I want a brother to play this game with me too
maybe if I ask my girlfriend... mmh better not
