I'm still trying to figure out how party size fits into the equation.

I just ran the same test with a max armor tank in party (duo party), and with my 1444 armor, I took on about 12% more damage than what I took on when solo. Not sure where this fits into the equation, but it's missing a variable somewhere that I'm still trying to work out. I'm not sure if the baseDamage is a ratio based on average armor value or if there is simply a static multiplier/divisor based on party size.

Still need more data to figure out how it works with parties.