2022-12-08 : If multiple replacement effects apply to a player or permanent being dealt damage, that player or the controller of that permanent chooses the order to apply them, not the controller of the source of damage.

2022-12-08 : If multiple sources would deal damage to an affected target at once, that target or that target’s controller chooses which source’s damage to prevent for each “shield.”

2022-12-08 : If some of the targets become illegal, the original division of prevention effects still applies, but the effects that would have been created for illegal targets aren’t created at all.

2022-12-08 : You divide the prevention effects as you cast Remedy, not as it resolves. Each target must be assigned at least 1 prevention “shield.” You can’t choose more than five targets and assign none to a target.