Here is an example of a split damage ability.
"After 6 sec, he charges to the player, inflicting 864871 Frost damage, split between all players within 8 yards of the target and knocking them back."
So if you have 2 players soaking, each will take around 430k damage.
If one of the players is immune to damage, will the damage still be split but 1 person takes nothing? Or since that person is immune to damage, will 1 player take everything?