The damage done by magic reflect,
is not based on the damage done by the attacker!
...
it's based on the attacker's damage!
The difference reveals itself when a blast from magic kills an enemy that is using silence to lower their damage. I have captured a replay here that shows this:
https://splinterlands.com/?p=battle&id=9b18d3a02b3a25ec36d221155251806f3d1e125f
watch closely at the amount of reflect damage taken by the ruler
won't change my strategies much, but I thought this was interesting.