Hello!
I haven't found anything about MDAS rules in Kill Team so I'm assuming this Bighammer rule applies to modifiers (like the Zealot specialism's Frenzied passive) and Strength: X2 weapons (like power fists and thunder hammers) in Kill Team too?
From the Designer's Commentary:
Q: If a rule modifies a model’s Strength
characteristic, and that model is equipped
with a melee weapon that also has a
modifier (e.g. ‘x2’), could you explain
the order in which the modifiers are
applied to the characteristics and the
weapon’s Strength?
A: First you must determine the model’s
current Strength characteristic. To do so
apply all modifiers to it that multiply or
divide the value, then apply any that add
or subtract to it. Having done this, you
then modify this value as described by the
weapon’s Strength characteristic.
For example, let’s imagine a model with a
basic Strength characteristic of 3 is under the
effects of two psychic powers: a friendly one that
doubles their Strength characteristic, and an
enemy one that subtracts 1 from their Strength
characteristic. That model’s current Strength
is therefore 5. If this model then fights with a
weapon like a power fist, which has a Strength
characteristic of ‘x2’, that attack will therefore be
resolved at Strength 10.