Sustain

When an effect is "sustained", it means you can keep it going by spending an action each round to sustain it.

Sustained effects are written as either "sustain (action type)" (e.g. "sustain swift"), or "sustain (action type) 3-rds" (e.g. "sustain free 3-rounds").

When no duration is specified, the effect must be sustained every round to keep it active, and ends immediately if you fail to sustain it on your turn. When a duration is specified, the effect can persist on its own for up to that duration, but that duration does not diminish on rounds where you sustain it. If you fail to sustain the effect on your turn, the duration begins to diminish as normal, and the effect ends when the duration expires.