jgsugden
Legend
Assassinate provides two advantages. Each has different rules for when it can be used.
You gain advantage on attack rolls against any creature that hasn't taken a turn in the combat yet. If they're surprised, that could be a few different times. During the surprised round, during your action before they act in the round following surprise, when you get a reaction attack from another PC's action, etc...
In addition, any hit you score against a creature that is surprised is a critical hit. The DM determines who might be surprised - although guidelines for when a character might be surprised are provided in the rules. However, the rules do not specify when surprise ends. That is up to the DM until they clarify - but most DMs would likely say it only lasts for the first round of combat as the direct benefits / penalties from being surprised end at that point.
So, advantage until a creature acts, and criticals during a surprise round versus creatures that are surprised is my take on it.
You gain advantage on attack rolls against any creature that hasn't taken a turn in the combat yet. If they're surprised, that could be a few different times. During the surprised round, during your action before they act in the round following surprise, when you get a reaction attack from another PC's action, etc...
In addition, any hit you score against a creature that is surprised is a critical hit. The DM determines who might be surprised - although guidelines for when a character might be surprised are provided in the rules. However, the rules do not specify when surprise ends. That is up to the DM until they clarify - but most DMs would likely say it only lasts for the first round of combat as the direct benefits / penalties from being surprised end at that point.
So, advantage until a creature acts, and criticals during a surprise round versus creatures that are surprised is my take on it.