since we read its going to be in some next beta i wanted to start this discussion
as usual im not a big fan of rng and i have a VERY BAD memory of mom dispel
it was FRUSTRATING most of the time, sometimes just dispeling EVERYTHING on the field(with disenchant area), sometimes just not even a stupid buff
also it was completely anti strategical to not have a idea of what you were paying for
as for the last point i suppose its possible for stardock to script dispel to show how much % of succes you have with a given mana/resource spent (Which is a solution i half like)
my idea instead was thinking something no luck based but completely skill based, i had a good idea for mom, but there we had much more mana so im thinking on elemental something like
dispel mana cost= enemyspelll mana cost(so the more powerful spell is cast the more you have to spend) +difference in INT between the 2 casters (this would be the strength part, the more intelligent is the enemy the more i have to pay to dispel)+shards used(in case you are going to dispel a uber demon who required 5 shards wouldnt be fair to just pay a few mana)+k (dunno if there is going to be spell levels or something else i cant think of)
post your own ideas if you have something in mind