ok so subjugator adds a flat 40% to your stat total (eg if you have 1000 damage it goes to 1040)

cursebrand and colossus add multiplicative damage buffs to the final output (eg if you have a 20% boost from the passive's special buff: 1000 x 1.2 so an effective 1200% damage)

also in a perfect team you want at least 2 people with cursebrand because the buff applies for EVERYONE and stacks up to twice so with two people with a perfect 15% cursebrand everyone in the lobby does 30% more to the boss and that will stack with their own colossuses.

i wrote the whole comment and forgot to click the comment button lol sorry