I have a sorcerer with a Gem Scarab familiar planned for a campaign starting at level 10, which would give the familiar 10 HD, which is more than enough for a Gem Scarab to advance a size category. This brought me to a couple issues:

  1. Does advancing a size category retroactively remove benefits its Monster Manual entry gave it for being small and/or provide any other changes, and

  2. Does the increase in HD due to being a familiar warrant an increased size category?

Also, would the increased Intelligence change anything else about its stats compared to what was presented in the Monster Manual entry?

  • \$\begingroup\$ For the record, there is a table for advancing monsters by size in MM. Familiars still don't do that. \$\endgroup\$ May 5, 2013 at 12:17

1 Answer 1


Familiars don’t actually gain HD

They simply are stated to be treated as if they had HD equal to their master’s for the sake of spell effects and the like. As a result, they don’t increase in size category, don’t gain separate HP, save bonuses, feats, skill points, and so on (though those last four are covered by the familiar setting them based on the master)

The increase in Intelligence improves the sorts of commands and concepts that the creature can understand, which is the main benefit, and potentially could increase things like Save DCs for creatures that use Intelligence for them.

  • \$\begingroup\$ Ah, ok. Similar question: is it possible to start with a larger version of the monster based on your HD total when you obtained the familiar? \$\endgroup\$
    – Cobalt
    May 5, 2013 at 18:21
  • \$\begingroup\$ @Cobalt I'm aware of no option for doing that. The usual rule is that "Only a normal, unmodified animal may become a familiar." Of course, Improved Familiar also says "The list in Table: Improved Familiar by Alignment presents only a few possible improved familiars. Almost any creature of the same general size and power as those on the list makes a suitable familiar," which means you could convince your DM that an advanced version of one of the creatures is suitable. Entirely up to the DM, though. \$\endgroup\$
    – KRyan
    May 5, 2013 at 18:23

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