Disclaimer: The intention of this rule is to make attacking from stealth more realistic, while defining exactly when a creature is surprised. The rule makes it easier to keep track of who can use reactions, and allows players to choose their initiative order during an ambush.
Consider this situation: A rogue sneaks up on an NPC, the Rogue passes a stealth check but rolls a lower initiative than the NPC. RAW the NPC is no longer surprised, and can use a reaction against the Rogue. It is also possible that the DM rules the NPC is not surprised. The NPC then gets their turn before the Rogue, making the previous stealth check pointless.
Some DMs have solved this by allowing attacks before initiative is rolled. However, this opens up the possibility of creatures getting an attack before combat, and then two full turns during combat, before the enemy can do anything. Plus, the decision of who is surprised still needs to be made, and creatures become unsurprised at different times, which needs to be kept track of. This rule eliminates some of these strange situations and alleviates some work from the DM.
Ambush: An ambush occurs when a hidden creature attacks another creature that is not engaged in combat. Creatures can plan an ambush by deciding an initiative order before attacking. The order must be communicated somehow, for example verbally or through hand signals. A party can also decide to have a default initiative order. If no order is planned, the attackers roll amongst themselves at the time of the ambush.
Executing an Ambush: The creatures executing an ambush must be hidden (unseen and unheard) from the creatures being ambushed. The creatures executing the ambush are put at the top of the initiative order, regardless of any other creatures’ initiative rolls. Initiative for all other creatures may be rolled before or after the ambush is executed.
Surprise: When an ambush occurs, any creatures that will roll initiative, and that were not aware of the attackers, are surprised. Surprised creatures can't use reactions, and stop being surprised when all attacking creatures involved in the ambush have finished their turn.
Notes:
An ambush cannot be executed against creatures that are already engaged in combat. If combat begins before the ambush begins, initiative is rolled as normal.
Creatures must conceivably be able to execute the ambush at the same time. In other words they need to be able to see the first attack, or have some sort of signal to begin.
If other creatures join the fight after both initiatives are rolled, they are put at the bottom of the initiative order.
Example Situations:
A group of PCs sees a group of orcs camping in the distance. They talk amongst themselves and decide to stage an ambush by sneaking up on the group and attacking in a specific order. The PCs pass their stealth checks to approach the group, and begin their attack. The DM adds the players to the top of the initiative list, in the order that they chose. Each player then gets a full turn of combat. During this time, the Orcs are surprised and can’t use reactions. After each player has taken their turn, the DM rolls initiative for the surviving Orcs. The orcs are all placed underneath the players in initiative, and they immediately take their turns. The initiative order remains the same for the rest of combat.
A group of Goblins sneaks up on a group of players by passing stealth checks. They all attack the players at once, so the DM rolls initiative for the goblins and places them at the top of the initiative order. The players also roll initiative amongst themselves, but are put underneath the goblins. During the attack, the players are surprised and can’t take reactions. After all goblins have had their turn, the players are no longer surprised, and combat continues as normal.
A single Rogue PC sneaks up on an NPC by passing a stealth check. The Rogue chooses to attack, so they get a full turn of combat. During this turn, the NPC is surprised, and can’t use reactions. As normal, the rogue would only have advantage on their first attack, as they would no longer be hidden afterwards. If the NPC survives, they get a full turn of combat, and there is no need to roll initiative, since the order is: PC, NPC.
A Rogue PC and a Sorcerer PC sneak up to a group of kobolds, while the rest of the party remains out of line of sight. The rest of the party can’t see the ambush taking place, and have no way of knowing when the ambush will begin, so they can’t participate. The Rogue motions to the Sorcerer to cast a Fireball. The Rogue tells the DM that he will attack immediately after the Sorcerer. So the Sorcerer is first in initiative order, and the Rogue is second. At this point the DM can decide to roll initiative for the kobolds and the other PCs, or they can wait until the two finish their attacks. Either way, the Sorcerer and Rogue will remain in the first and second positions, and all other creatures will roll initiative as normal.
A party consists of a Fighter, Wizard, and Rogue. They approach a bandit camp from the woods. The Fighter and Wizard decide to remain in the forest while the Rogue sneaks into the camp. They have previously decided to use a bird call as a signal to begin an ambush. They decided the rogue will attack first, followed by the Fighter and Wizard in no particular order. The Rogue passes stealth checks to get deep within the camp. He makes the bird call, which requires a performance check. On a success, the Rogue is put at the top of the initiative order, while the Fighter and Wizard roll for second and third position. On a failure, the bandits may immediately notice the Rogue, in which case initiative will be rolled as normal.
Disclaimer: The intention of this rule is to make attacking from stealth more realistic, while defining exactly when a creature is surprised. The rule makes it easier to keep track of who can use reactions, and allows players to choose their initiative order during an ambush.
Consider this situation: A rogue sneaks up on an NPC, the Rogue passes a stealth check but rolls a lower initiative than the NPC. RAW the NPC is no longer surprised, and can use a reaction against the Rogue. It is also possible that the DM rules the NPC is not surprised. The NPC then gets their turn before the Rogue, making the previous stealth check pointless.
Some DMs have solved this by allowing attacks before initiative is rolled. However, this opens up the possibility of creatures getting an attack before combat, and then two full turns during combat, before the enemy can do anything. Plus, the decision of who is surprised still needs to be made, and creatures become unsurprised at different times, which needs to be kept track of. This rule eliminates some of these strange situations and alleviates some work from the DM.
Ambush: An ambush occurs when a hidden creature attacks another creature that is not engaged in combat. Creatures can plan an ambush by deciding an initiative order before attacking. The order must be communicated somehow, for example verbally or through hand signals. A party can also decide to have a default initiative order. If no order is planned, the attackers roll amongst themselves at the time of the ambush.
Executing an Ambush: The creatures executing an ambush must be hidden (unseen and unheard) from the creatures being ambushed. The creatures executing the ambush are put at the top of the initiative order, regardless of any other creatures’ initiative rolls. Initiative for all other creatures may be rolled before or after the ambush is executed.
Surprise: When an ambush occurs, any creatures that will roll initiative, and that were not aware of the attackers, are surprised. Surprised creatures can't use reactions, and stop being surprised when all attacking creatures involved in the ambush have finished their turn.
Notes:
Example Situations:
A group of PCs sees a group of orcs camping in the distance. They talk amongst themselves and decide to stage an ambush by sneaking up on the group and attacking in a specific order. The PCs pass their stealth checks to approach the group, and begin their attack. The DM adds the players to the top of the initiative list, in the order that they chose. Each player then gets a full turn of combat. During this time, the Orcs are surprised and can’t use reactions. After each player has taken their turn, the DM rolls initiative for the surviving Orcs. The orcs are all placed underneath the players in initiative, and they immediately take their turns. The initiative order remains the same for the rest of combat.
A group of Goblins sneaks up on a group of players by passing stealth checks. They all attack the players at once, so the DM rolls initiative for the goblins and places them at the top of the initiative order. The players also roll initiative amongst themselves, but are put underneath the goblins. During the attack, the players are surprised and can’t take reactions. After all goblins have had their turn, the players are no longer surprised, and combat continues as normal.
A single Rogue PC sneaks up on an NPC by passing a stealth check. The Rogue chooses to attack, so they get a full turn of combat. During this turn, the NPC is surprised, and can’t use reactions. As normal, the rogue would only have advantage on their first attack, as they would no longer be hidden afterwards. If the NPC survives, they get a full turn of combat, and there is no need to roll initiative, since the order is: PC, NPC.
A Rogue PC and a Sorcerer PC sneak up to a group of kobolds, while the rest of the party remains out of line of sight. The rest of the party can’t see the ambush taking place, and have no way of knowing when the ambush will begin, so they can’t participate. The Rogue motions to the Sorcerer to cast a Fireball. The Rogue tells the DM that he will attack immediately after the Sorcerer. So the Sorcerer is first in initiative order, and the Rogue is second. At this point the DM can decide to roll initiative for the kobolds and the other PCs, or they can wait until the two finish their attacks. Either way, the Sorcerer and Rogue will remain in the first and second positions, and all other creatures will roll initiative as normal.
A party consists of a Fighter, Wizard, and Rogue. They approach a bandit camp from the woods. The Fighter and Wizard decide to remain in the forest while the Rogue sneaks into the camp. They have previously decided to use a bird call as a signal to begin an ambush. They decided the rogue will attack first, followed by the Fighter and Wizard in no particular order. The Rogue passes stealth checks to get deep within the camp. He makes the bird call, which requires a performance check. On a success, the Rogue is put at the top of the initiative order, while the Fighter and Wizard roll for second and third position. On a failure, the bandits may immediately notice the Rogue, in which case initiative will be rolled as normal.