1st Summon Arachnid (Su): Once per day you may summon a small spider or scorpion as per the summon monster spell (the arachnid does not have the fiendish template). At level 6 the size of the creature increases to medium, At level 10 the size of the arachnid increases to large, at level 14 the size of the arachnid summoned increases to Huge, at level 18 the size of the arachnid increases to gargantuan. You may instead summon 1d3 spiders of one size category smaller or 1d4+1 spiders of two size categories smaller.
2nd Spider Climb (Su): You may climb on walls as per the spider climb spell for 1 minute per caster level per day. These minutes need not be continuous.
4th Poison (Sp): You can cast poison 1/day.
8th Giant Vermin (Sp): You can cast giant vermin 1/day.
12th Insect Plague (Sp): You can cast insect plague 1/day.
16th Creeping Doom (Sp): You can cast creeping doom 1/day