The material below is Open Game Content from a 3PP Source
You gain the ability to summon powerful spiders.
Prerequisites: Ability to cast summon monster or summon nature’s ally spells, drow.
Benefit: When casting either a summon monster spell or a summon nature’s ally spell, your options increase. Depending on the level of the spell, you can summon the spiders listed below.
Creatures marked with an asterisk (*) are summoned with the celestial template if you are good, and the fiendish template if you are evil. If you are neutral, youmay choose which template to apply to the creature. Furthermore, when you summon spiders using summon monster or summon nature’s ally, the DC of the summoned monster’s poison and web effects increases by 2.