My question is if, during a combat, I introduce a second wave of enemies (the party is fighting 10 goblins but then a second party of 5 who were flanking/hiding joins on the second round), when can this second wave act? If they join on the second round can they act on that round or have to wait till round 3. This question specifically refers to D&D 5e.

  • 5
    \$\begingroup\$ Hello there! Welcome to RPG.SE! Take the tour and visit the help center to have some guidance in posting questions and answers here! When you write a question, you should add the tag denoting the game you are playing and the edition, in case there are more than one. For example, th tag [dnd-5e] denotes Dungeons and Dragons - 5th edition. \$\endgroup\$
    – Eddymage
    Commented Nov 15, 2022 at 9:33
  • 1
    \$\begingroup\$ Related, possible duplicate: How do I handle initiative when a new force joins a combat that's already in progress? I think whether or not this is a duplicate hinges on whether OP is specifically asking about adding a new group who have the SAME STAT BLOCK as the original combatants, in this case adding 5 more goblins to a fight where there are already 10 goblins. \$\endgroup\$
    – Kirt
    Commented Nov 19, 2022 at 20:51
  • \$\begingroup\$ When you say "on the second round", do you mean the new monsters are joining at the very beginning of the round, or some time during the round after some characters ave already had their turns? \$\endgroup\$ Commented Nov 22, 2022 at 0:45

1 Answer 1


They act on their own initiative count

Each creature acts on their initiative order during combat. So when a new group enters combat, you will need to determine the starting positions and initiative for them to know when they act.

The rules for this are on page 189, PHB, under Combat Step by Step. As we are already in combat, you can skip the pre-combat surprise part. Then you get to:

2. Establish positions. The DM decides where all the characters and monsters are located. Given the adventurers’ marching order or their stated positions in the room or other location, the DM figures out where the adversaries are—how far away and in what direction.

Nothing changes here. You establish the starting positions for the newly arriving monsters. It may be useful to have these around corners etc., outside immediate combat, so they do not "magically" appear and start to act. If you do this, they will probably spend part of their first round moving into sight. Next, you establish initiative:

3. Roll initiative. Everyone involved in the combat encounter rolls initiative, determining the order of combatants’ turns.

All other parties already have rolled initiative. The new arrivals have not, so you roll initiative for them. Generally, the DM makes one initiative roll for each group of identical creatures:

The DM makes one roll for an entire group of identical creatures, so each member of the group acts at the same time.

Rolling only once for large groups can have unwanted effects, as all the monsters acting on the same count get to act one after another and can coordinate their actions against the PCs in ways they could not if they had individual initiative.

Therefore, most DMs roll a new initiative for new groups entering an ongoing combat, even if it is the same type of monster -- it is a new group, after all, and the PHB tells you to roll once per group.

So, if your new monsters joined on the second round from their hiding place, you would roll initiative for them at the start of the second round, determine when it's their turn in the initiative order, and have them move and/or attack then. They would not have to wait until the third round.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .