In the Advanced Class Guide there is a new spell: Whip of Spiders.
There are also two follow on spells Whip of Centipedes and Whip of (Army) Ants.
All of these are in the Conjuration (Summoning) school.
Are you proficient with this weapon?
Does the whip deal its own damage in addition to the swarm damage?
Does the swarm benefit from augment summons (for poison and distraction DCs) while it is a whip?
Whip of Spiders
School: conjuration (summoning);
Level: bard 2, druid 2, sorcerer/wizard 2, summoner 2, witch 2
Casting Time: 1 standard action
Components: V, S, M/DF (a square of red cloth)
Range: 0 ft.
Effect: whip like swarm
Duration: 1 round/level (see text)
Saving Throw: none;
Spell Resistance: yes
You summon hundreds of Diminutive spiders, which cling
together in the form of a whip made for a creature of your
size. You can wield this object as if it were an actual whip,
except you make a melee touch attack with it instead of
a regular attack. Any creature you strike with the whip
takes swarm damage as if it were attacked by a spider
swarm (1d6 points of damage plus poison and distraction,
Bestiary 258). The swarm whip is able to damage creatures
with armor or natural armor, even if a normal whip could
not. It cannot be used to make bull rush, grapple, or trip
attacks, and (unlike a swarm) is subject to a miss chance for
concealment and cover.
The whip is immune to all weapon damage, is never
staggered or reduced to a dying state by damage, and
is immune to any spell or effect that targets a specific
number of creatures (including single-target spells such as
disintegrate). The whip takes half again as much damage
from spells or effects that affect an area, but since it is
considered part of your gear, it takes damage only if you fail
a saving throw on a 1 or if it is specifically targeted by an
opponent. The whip does not have a swarm’s susceptibility
to high winds.
As a standard action, you can transform the whip into a
spider swarm (all squares of the swarm must be within 15
feet of you); thereafter it functions as summon swarm. The
spider swarm has 3 hit points and persists in that form for
2 rounds or until the end of this spell’s duration, whichever
This spell is just like other spells that have come before it - flame blade, mage's sword, spiritual weapon... Spells that have been around since forever, so this isn't really new, and we can easily divine rulings based on those precedents. In fact, flame blade is just about exactly the same in nature (different school, but whatever).
It doesn't "also" do weapon damage, they just do the damage listed. No reference, that's just how we all know all those spells work.
All those spells behave like weapons in terms of other feats, effects, etc. - see this entry in the Paizo FAQ. Weapon Focus, Arcane Strike, bard song, etc.
As it's conjuration(summoning), yes, augment summoning would work just as it does on a normal swarm. The effect is a "whip like swarm." Its benefits are modest but functional. Since it can turn into a swarm it would be weird to have different DCs in one form than the other.
It's a spell that summons a swarm that then acts like a weapon. I know that's somewhat confusing but in the end, it's pretty cool, so use your best judgement.
Oh yay, another Paizo guessing game. Turns out there are answers to these, but ⅔ are from a random forum post and ⅓ are based on some very strange and nonsensical rules.
This is defined in a random forum post by a Paizo developer. They have never, to my knowledge, issued an official errata or even added it to the FAQ, but spell effects that behave like weapons are not weapons and do not require proficiency, according to Joshua Frost. Thanks to mxyzplk for finding the link; I certainly never would have.
Per the same link above, no. Wielding, in this case, appears to mean only for the purposes of attacking and range and things, but not the effects of the whip itself.
No. According to the spell, the whip is an object:
You can wield this object
Objects are, by definition, not creatures, and Augment Summoning only affects creatures.
Yes, that means it’s an object, a non-creature, made up of still-living creatures. No, this doesn’t make sense. I suggest houseruling it into being a living weapon, similar to intelligent weapons, and letting Augment Summoning work on it, but that’s not in the rules.