New rules: How does Cycle of the Storm work out?

[Jupiter]

So with the new models new questions!

The Lord Arcanum has an ability to return slain models:

Cycle of the Storm

Once per turn, when a friendly Stormcast Eternal model is slain within 18" of this model, instead of removing the slain model, you can heal 1 wound that has been allocated to it.

What is unclear to me is when you can decide to bring back a slain model. Can you wait until all models have wounds allocated to them? for example 3 wounds are done to a unit of Liberators (2wounds), do you have to activate the ability after 2 wounds are allocated and then bring back the model and then allocate the third wound to it or can you first allocate all the wounds and then have 2 liberators on 1 wound.

How does it work with single models if wounds are spilled over, for example 6 wounds are done on a Celestant on foot (5wounds), if you bring back the models is the "lost" damage still allocated to it thus still killing it or is it wasted and the model is back on 1 wound?

[Turragor]

My  thoughts (caveat - I think it needs an FAQ anyway as it ranges from super good to useless based on interpretation - which is too great a variance imo!?

On a multimodel unit, it's clear; the model returns but the unit is still there to take the full wounds. So those wounds 'wait' while that model is slain and returned. So in multiwound model units, that model takes the next wound again as the wounds have to go to the wounded.

Result - You save 1 wound. It's kind of pointless unless it's like the last wound on a fulminator or something.

On a character unit, it's unclear. Wounds are allocated one at a time and stop being allocated to a model when it is slain. This ability triggers when a model is slain. It is slain but not removed.

The model is slain, the unit is gone, the wounds are lost, the model removed... then it returns with a wound.

Result - Wounds gone, model saved with 1 wound. New sources of damage can take that wound off. It's not subsequently immortal or anything.

 

The core question is then, do wounds wait to be used on the unit again. Does the unit 'disappear'. If you can have an empty unit with no models at any point, that seems a bit ridiculous to me.

Some might argue that it's not slain (and I can see some merit to that argument I just disagree with it) but the rule looks a lot like the phoenix rule and even more like the artefacts that return characters to life (and I've never seen a spillover wound argument there).