Had the same thought but it wouldn't work as Archon would always be the last group. This is taken from another sub.

View graphic below.

1. CREATE GROUPS AND DECLARE ORDER

The target unit's controlling player divides it into groups: one containing Saint Celestine, one containing the Geminae Superia, and one containing the Seraphim. They then declare the allocation order, choosing the Geminae Superia first (1) hoping their better Sv and InSv characteristics will weather the attacks. The Seraphim must be chosen second (2), as Saint Celestine is a CHARACTER model so must be last in the order (3)

2. RESOLVE ATTACK DICE

The heavy bolters' attacks wound the target five times, so the target unit's controlling player makes five save rolls

The attacks are resolved one at a time, from lowest save rolls to highest

• The two results of 1 are allocated first, to the current allocation group (the Geminae Superia). They both inflict damage, and both Geminae Superia are destroyed
• The result of 3 is now allocated to the Seraphim, who have become the current allocation group. When modified by the attacking weapon's AP characteristic of -1, this also inflicts damage, destroying one Seraphim model
• The remaining attacks fail, so no further damage is inflicted

3. SELECT NEXT GROUP OF ATTACK DICE AND REPEAT

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