Since 1.21 (or 1.20.5? I can't keep track of the two 😅 ) added new attribute modifiers/operations, it seems all of Magic's item attributes conflict with each other & cannot stack.

In the new version, every item's attribute modifier has to be given a unique ID, and two items with the same attribute modifier ID won't stack. For example, a Chestplate that adds +2 armour with the ID "test_id" won't stack armour with Boots or Leggings that also have the ID "test_id", instead they overwrite each other's armour value.

Magic seems to set this ID automatically as magic:modifier which means all wands that grant attributes such as attack damage, armour, movement speed, max health etc, will NOT stack with each other & instead conflict with each other, meaning wearing multiple armour-wands will not grant the user the armour bonus of each individual piece, since all their IDs conflict.

On the bright side though, Magic does seem to be supporting the new attributes such as scale when added to wands/mobs/etc, as follows:

  item_attributes:
    scale: 4

The only issue with these seems to be the conflicting IDs again, and setting the operation such as add_base add_multiplied_base and add_multiplied_total (though I might be forgetting something, as I vaguely recall being able to set these operations somewhere)