Is this house-rule that has each monster/NPC roll initiative separately (even when there are multiple creatures of the same kind) game-breaking?

Question

The rules for initiative in PHB read (emphasis mine):

Initiative determines the order of turns during combat. When combat starts, every participant makes a Dexterity check to determine their place in the initiative order. The DM makes one roll for an entire group of identical creatures, so each member of the group acts at the same time.

The DMG offers several variant rules for initiative besides the above ruling: Initiative Score (i.e. a passive Dexterity check, rather than an active roll), and Side Initiative (each group rolls a d20, without modifiers), and Speed Factor (more uncertainty, less speed). For large groups of enemies, some DMs decide to split them into subgroups (see Greenstone Walker's answer to "How does having monsters of the same type go at the same time affect balance?"). I find the ruling about initiative in PHB asymmetric\$^1\$ and none of the listed alternatives really satisfies me.

Would a house rule that allows rolling initiative for each\$^2\$ enemy (even of the same type) be a game-breaking one? Or would there be just minor problems at most?

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\$^1\$ I wonder why the PCs can have all different initiative rolls while monsters (even of the same type) should share the same one. They are still different individuals which may react with different speed.

\$^2\$ Do not consider here the issue of rolling a lot of d20s for the initiative (if you consider it a problem).

Answer 1

I usually do this, but it can become difficult when the enemies are numerous.

This is what I usually do for initiative, and most of the time, it causes no issues at all. It is when the number of NPC combatants gets to be large that individual initiative starts to get cumbersome.

I once ran a battle against four NPCs with 8 bears and rolled them all individually, and I lost track of which bear was which after the first round. The utility of rolling the group at the same time is that you don't have to distinguish between them in the initiative order. It doesn't matter which bear is which, they all go at the same time.

This is not a game balance concern.

If anything, this eliminates a possible game balance concern. Rolling the entire group at once gives the DM the opportunity to dogpile a character without them or their allies having a turn in between attacks from the NPCs. To be clear, I never would have dogpiled one character with 8 bears, but rolling initiative individually makes that less feasible of a tactic for the DM to pull.

Answer 2

In Virtual Tabletops (VTT), it's the standard.

If you play in on-line or virtual environments, like Roll20, this is usually the norm. I use tools that roll initiative for everything simultaneously and the Initiative Tracker points to which specific token is playing now. Makes the game less swingy (as turns are usually evenly distributed across both sides) and has no downsides...

...except if you have a horde of enemies (like 40 low-hp zombies). Going through each one's initiative is a hassle even then. I only had it happen a couple of times. The first one was chaos. The second, I grouped initiatives.

In actual table-play, it becomes a mess if you have over 3-5 identical mobs, in my experience. That's why we tend to group things up. If you have a good memory, you can do it for larger groups, or even ask your players to track initiative for you (we have a custom tracker with clothespins for each entity). Downsides are as you pointed out: more swingy (suddenly you can have 5 mobs attacking first without any party member being able to react), and not as reactive to whatever is happening in the fight.

Answer 3

Volo's Guide to Monsters actually suggests that for Kobolds the GM should not group initiative rolls as usual and instead split the group of kobolds up so as to replicate a swarm attack and not give the players a chance to regroup or act as one.

So at least one occasion of RAW being not to do this. In the Kobolds: Little Dragons - Tactics section of Volo's Guide to Monsters, we see:

In a combat involving large numbers of kobolds (such as ten or more), consider spreading out their attacks over the round instead of having them all act on the same initiative count. Doing this gives the kobolds more opportunities to react to what their enemies do, and makes it harder for players to coordinate their characters’ attacks because not all the kobolds take their actions at the same time.

Answer 4

Game breaking in the sense of making the game much harder or easier for the players?

No.

Game breaking in the sense of the DM's brain hurting?

For sure, as soon as you have more than a handful creatures in combat. The rule exists because most people can't (or don't want to) track 15 mostly identical creatures in combat.

Individual initiative for more than 5 or so creatures quickly drains the game of speed and seriously increases the amount of bookkeeping the DM needs to do. It will increase the number of mistakes, which either annoys the players or slows the game even further as they get corrected.

In return for the extra tediousness, it basically offers you... nothing. The breakdown in speed is likely to completely destroy the immersion, and people will quickly stop caring that Orc #152 might react slightly faster than Orc #153 and instead wonder if they've got time to go outside for a smoke while the DM resolves all the monsters and their turn comes round again.

I've tried assigning individual initiative to each monster in the past, but I reverted back to base rules after the very first encounter. It's not worth the headache, I have a game to run.

Answer 5

It is not game breaking

It is not even a house rule. Rolling initiative for each participant explicitly described in the PHB:

When combat starts, every participant makes a Dexterity check to determine their place in the initiative order

The PHB also adds that

The DM makes one roll for an entire group of identical creatures

So if creatures are identical, the DM makes one roll for them.

You, the DM, claimed that

They are still different creatures which may react with different speed

As being said by the DM, these participants are different creatures, therefore they are not "identical", therefore each makes a Dexterity check to determine their place in the initiative order.

The rules serves you, not vice versa

DMG Chapter 8: Running the Game

The rules allows you, the DM, to decide when the creatures are identical to that extend they have the same initiative. You either make them having the same initiative or roll individually, your choice. It is not "a possibly game-breaking house rule", it is how the game is supposed to work.

Using the same initiative is a tool for easier initiative tracking, not for making encounters more balanced. Quite the opposite, sharing the same initiative can make the group's first attack substantively stronger. That's why Volo's Guide to Monsters suggests to ignore this rule for Kobolds, for instance (see Richard C answer for details).