Changing Size of a Monster

[Bathman]

Hello all! I was putting my party up against a Shambling Mound, and it seems more fitting for the situation for it to be Huge size. I make all the adjustments and whatnot, but I get to CR, and I can't find any information on what changing size does to it. So, in summary, making my creature bigger, does the CR change at all?

[Deighton Thrane]

Have you used a template like the Giant template, or have you simply changed the creatures size? Because using a template usually increases CR. The monster creation rules in the bestiary have certain guidelines for monster creation, and list minimum CR a monster should be to be for certain sizes, but doesn't state that increasing size increases CR.

So template: yes. No template: no.

[Bathman]

No templates. Just increasing the size via the Monster Advancement charts.

[Deighton Thrane]

If you mean you've applied the changes from table 2-2 large -> huge, so +8 str, -2 dex, +4 Con and +3 natural armor, then I would say yes you increase the CR, as that's the same as applying the giant creature template, except for the larger boost to strength.

But it doesn't actually say that in the monster advancement section, since they work under the premise that you're building a certain CR version of a creature, and then tell you how to adjust the stats to fit that CR, not how changing certain stats will alter the CR of the creature.