EL Modifiers for Multiple Monsters

[Matthias]

Going by the DMG's formula for EL modifiers for multiple monsters, I'd like to know what all of your thoughts are on how well it works and how far it can be extended. But is it really so simple?

EL Modifier
+1 or +2 = 2 monsters of equal CR
+3 = 3 monsters of equal CR
+4 = 4-5 monsters of equal CR
+5 = 6-7 monsters of equal CR
+6 = 8-11 monsters of equal CR
+7 = 12-15 monsters of equal CR
+8 = 16-23 monsters of equal CR
+9 = 24-31 monsters of equal CR
+10 = 32-47 monsters of equal CR
+11 = 48-63 monsters of equal CR
+12 = 64-95 monsters of equal CR
+13 = 96-127 monsters of equal CR
+14 = 128-191 monsters of equal CR
+15 = 192-255 monsters of equal CR
+16 = 256-383 monsters of equal CR
+17 = 384-511 monsters of equal CR
+18 = 512-767 monsters of equal CR
+19 = 768-1,023 monsters of equal CR
+20 or more = 1,024+ monsters of equal CR

Of course, there can be extenuating factors (where two monsters of different species can play off each other's abilities and be a more dangerous threat than if they were two of the same one or the other species).

But how reliable is the formula?

[edit: corrected for terminology ]

 

[Nail]

Going by the DMG's formula for CR modifiers for multiple monsters....?

You mean: "EL modifers for mutiple monsters", right?

 

[Magesmiley]

Well, a lot of it is going to depend on the situation really. Let's take a pack of gnolls. CR1 each. According to the progression you cited, 20 of them would be:
+8 = 16-23 monsters of equal CR

So, an EL of 9. Are they really that? 1 Fireball from a 9th level wizard and the encounter is essentially over. Is that really using up 25% of the group's resources? I doubt it. So, in this case they aren't really much more than a nuisance to the party.

Exending the chart has issues when there are significant disparities between the creatures and the players. Be careful when the party's level is more than around 5 levels higher than the actual CR of the creatures - the chart starts to break at that point.

That's not to say that the progression isn't useful still above +5 - I DM for a group of 6-8 characters. An average encounter for them is typically 1-2 levels above their actual level, however I typically make this up by tacking on additional creatures rather than upping the power of individual opponents.

 

[Tsillanabor]

Typically I give +1 for each doubling of numbers past 1.
4 1/4 CR=EL 1
8=EL 2
16=EL 3

I figure for higher CR critters I'll have to revise it.