How do split damage abilities work if someone is immune to damage in World of Warcraft?

https://www.wowhead.com/spell=299914/frenetic-charge

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?

Solution 1:

Base damage is split between each player in the affected area. This damage is then individually processed for each player with regards to immunities, damage reduction effects, absorbs and increased damage taken events. So any active immunities cut a sizeable chunk out of the damage the healers need to heal.

The core logic behind this is that determining who takes the damage doesn't happen at the same time as determining how much damage each player takes. The game isn't going to mess around with slightly shifting damage from one player to another in order to ensure that all players take their fair share of damage. That would totally defeat the point of having damage reduction effects active on players.