The numbing traps passive text reads:
Enemies you Slow or hit with Fan of Knives, Spike Trap, Caltrops, Grenades,
and Sentry fire have their damage reduced by 25% for 3 seconds.
Let's say you're in a game with 4 Demon Hunters, all running the numbing traps passive. Would the damage reduction from these passives stack? If so, I'm assuming they stack multiplicatively.
You are correct, these stack multiplicatively. Here is a reddit with some empirical data testing a similar damage reduction from a monk.
Each one is assessed in some order determined by the game, so really the reduction for 4 players would be
damage = total * (1 - 0.25) * (1 - 0.25) * (1 - 0.25) * (1 - 0.25)
Which means the total damage reduction is going to be
1 - (0.75^4) = 0.68359375
Which is is roughly 68.4% from 4 stacks of 25% damage reduction.
25% reduction for 1-4 players:
