Is damage reduction applied before Unity splits damage, or after?

There's a ring, Unity, that splits damage among all people wearing it.

When does damage reduction apply for this?

Let's say, for example, I've got a barbarian loaded up with armor and resists who is sitting in a molten pool that does 50,000 damage per second, but with all his damage reduction he's got 90% resistance so it drops to like 5k/sec and he pretty much ignores it. Now let's say he and a mage friend of his put Unity on. Let's say the mage only has 50% damage reduction. When Unity splits the damage, is it going to be doing damage to the mage after the Barbarian's reduction (so, 2.5k/second) or will it be doing it before the Barbarian's reduction (so potentially 12.5k/second)?

The damage splitting effect works like this: For this example an attack does 100 damage, Player A's damage mitigation is 70% and Player B's is 50%.

• When A gets hit, the attack is reduced to 30 damage, then gets halved and both players take 15 damage.
• When B gets hit, the attack is reduced to 50 damage, then gets halved and both players take 25 damage.
• If there are 3 Players & A gets hit, the resulting 30 damage will result in each Player taking 10 damage.

As you can see,damage reduction is applied before the damage splits up(as true damage).