# The best Vulnerable-uptime builds apply it as an automatic side-effect of their main damage skill, not as a separate action

Whirlwind-style builds keep near-100% Vulnerable uptime because Vulnerable application is baked into the same skill already being spammed for damage (along with Bleed and Slow), rather than requiring a dedicated Vulnerable-setup skill and rotation slot.

Diablo IV patch 3.2.1. Category: uptime loop. Evidence: Likely.

## Detail
This is the general uptime-loop principle behind most 'set and forget' Vulnerable builds: any skill that both deals your primary damage AND applies Vulnerable removes the sequencing problem entirely, since every cast is simultaneously your damage and your setup.

## Why it works
Uptime loops are strongest when the buff-application step has zero opportunity cost - piggybacking Vulnerable onto your spam skill means there is never a choice between 'deal damage' and 'refresh Vulnerable.'

## How to use it
When choosing between two similar skills/Aspects, prefer the one that folds Vulnerable (or your build's other key debuff) into your main damage-dealing action over one that requires a separate cast.