uncommon n large animal swarm 

Perception +17; bonesense (imprecise) 30 feet, darkvision

Skills Acrobatics +17

Str -4 Dex +5 Con +4 Int -5 Wis +2 Cha -5

Bonesense A bone skipper swarm identifies bones and creatures with a skeletal system in the listed range.

AC  24; Fort +14, Ref +17, Will +12

HP 120; Immunities precision, swarm mind; Weaknesses area damage 9, splash

Speed 25 feet, fly 40 feet

Swarming Bites [>] Each enemy in the swarm's space takes 3d6 piercing damage (DC 24 basic Reflex save) plus exposure to marrow rot.

Marrow Rot (disease) Marrow rot affects only creatures with a skeletal system Saving Throw DC 24 Fortitude; Onset 1 day; Stage 1 enfeebled 1 (1 day); Stage 2 enfeebled 2 (1 day); Stage 3 enfeebled 2 and drained 1 (1 day)

AoE2, page 80.