Sorry, but I do not understand. For me it with savage attack rolls 1d8 + 1d8 + 4 (the savage attack). With a critical hit, wonder if he rolls over 1d8 (only attack) or roll it all over again, including the savage attack.
Savage attacks does not grant additional damage, it grants alternative damage.
Without a critical hit, you roll 1d8+4 and a different 1d8+4. If the first 1d8+4 is 5 and the second 1d8+4 is 7: You would deal 7 damage, not 12.
If you score a critical hit, then you would pick between 2d8+4 or 2d8+4. If the first 2d8+4 is 16, and the second 2d8+4 is 10: You would deal 16 damage, not 26.
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