So a quick question about the Carrionstorm: am I reading the statblock correctly in thinking it's a Large sized swarm, made up of Tiny creatures?
XP 400
NE Tiny undead (swarm)
Init +4; Senses darkvision 60 ft.; Perception +6
----------------------------
DEFENSE
----------------------------
AC 12, touch 12, flat-footed 12 (+2 size)
hp 11 (2d8+2)
Fort +1, Ref +0, Will +5
Defensive Abilities swarm traits; Immune undead traits
Weaknesses vulnerable to channeled energy
----------------------------
OFFENSE
----------------------------
Speed 10 ft., fly 40 ft. (good)
Melee swarm (1d6 plus distraction)
Space 10 ft.; Reach 0 ft.
----------------------------
STATISTICS
----------------------------
Str 1, Dex 11, Con —, Int 2, Wis 14, Cha 13
Base Atk +1; CMB –1; CMD 4 (can't be tripped)
Feats Improved Initiative
Skills Fly +12, Perception +6
SQ pallid bond
----------------------------
SPECIAL ABILITIES
----------------------------
Pallid Bond (Ex)
A carrionstorm never initiates an attack on a creature that openly wears a symbol of Urgathoa or that is itself undead. If attacked first by such a creature, the carrionstorm's swarm attack deals only 1d3 points of damage to that creature rather than the usual 1d6 points.
Vulnerable to Channeled Energy (Ex)
A carrionstorm takes 150% as much damage as normal from channeled positive energy.
Makes sense. Thanks for pointing it out to me! (The PCs are already paranoid about it - they know it's there, but not how many or how nasty it is.)
Yes, all swarms take up a 10 ft square (non-flying) or cube (flying), regardless of the size of the individual creatures (their size determines the total number of creatures in the swarm, which is rarely relevant for anything):
Swarm Subtype: A swarm is a collection of Fine, Diminutive, or Tiny creatures that acts as a single creature. A swarm has the characteristics of its type, except as noted here. A swarm has a single pool of Hit Dice and hit points, a single initiative modifier, a single speed, and a single Armor Class. A swarm makes saving throws as a single creature. A single swarm occupies a square (if it is made up of nonflying creatures) or a cube (of flying creatures) 10 feet on a side, but its reach is 0 feet, like its component creatures. In order to attack, it moves into an opponent's space, which provokes an attack of opportunity. It can occupy the same space as a creature of any size, since it crawls all over its prey. A swarm can move through squares occupied by enemies and vice versa without impediment, although the swarm provokes an attack of opportunity if it does so. A swarm can move through cracks or holes large enough for its component creatures.
A swarm of Tiny creatures consists of 300 nonflying creatures or 1,000 flying creatures. A swarm of Diminutive creatures consists of 1,500 nonflying creatures or 5,000 flying creatures. A swarm of Fine creatures consists of 10,000 creatures, whether they are flying or not. Swarms of nonflying creatures include many more creatures than could normally fit in a 10-foot square based on their normal space, because creatures in a swarm are packed tightly together and generally crawl over each other and their prey when moving or attacking. Larger swarms are represented by multiples of single swarms. The area occupied by a large swarm is completely shapeable, though the swarm usually remains in contiguous squares.