Spider Companion( Drow of the Underdark, p. 52)
Instead of an animal, you bond with a monstrous spider
Vermin Trainer (DrU) , animal companion,
You can select a monstrous spider as your animal companion. This spider gains all the benefits normally granted to animal companions. At 1st level, you can select a Tiny, Small, or Medium monstrous spider as your spider companion. A druid of sufficiently high level can select a more powerful creature as her spider companion, applying the indicated adjustment to the druid's level (in parentheses) for the purpose of determining the spider companion's characteristics and special abilities.
|Spider||Minimum Level (Adjustment)|
Spiders are not available as animal companions.