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.

You divide the prevention effects as Angel of Salvation's triggered ability is put onto the stack, 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.

If some of the targets become illegal for Angel of Salvation's ability, the original division of prevention effects still applies, but the effects that would have been created for illegal targets aren't created at all.

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."

You can tap any untapped creature you control to convoke a spell, even one you haven't controlled continuously since the beginning of your most recent turn.

Because convoke isn't an alternative cost, it can be used in conjunction with alternative costs.

Tapping a multicolored creature using convoke will pay for or one mana of your choice of any of that creature's colors.

When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Convoke applies after the total cost is calculated. Convoke doesn't change a spell's mana cost or mana value.

Tapping an untapped creature that's attacking or blocking to convoke a spell won't cause that creature to stop attacking or blocking.

If a creature you control has a mana ability with in the cost, activating that ability while casting a spell with convoke will result in the creature being tapped before you pay the spell's costs. You won't be able to tap it again for convoke. Similarly, if you sacrifice a creature to activate a mana ability while casting a spell with convoke, that creature won't be on the battlefield when you pay the spell's costs, so you won't be able to tap it for convoke.