Moonrat (CR 1/4)

Tiny Magical Beast
Alignment: Always evil
Initiative: +2 (Dex); Senses: darkvision 60 ft., low-light vision, and scent

AC: 14 (+2 size, +2 Dex), touch 14, flat-footed 14
Hit Dice: 1/4d10 (1 hp)
Fort +2, Ref +4, Will +3
Speed: 15 ft., climb 15 ft.
Space: 2 1/2 ft./0 ft.
Base Attack +0; Grapple -12
Attack: Bite +4 melee
Full Attack: Bite +4 melee
Damage: Bite 1d3-4
Special Attacks/Actions: -
Abilities: Str 2, Dex 15, Con 11, Int 2, Wis 13, Cha 2
Special Qualities: lunar mind, uncanny dodge
Feats: Iron Will; Weapon Finesse
Skills: Balance +10, Climb +10, Hide +15, and Move Silently +5
Advancement: -
Climate/Terrain: Any land and underground
Organization: Swarm (10-100)
Treasure/Possessions: None

Source: Monster Manual II

Lunar Mind (Ex): A lunar modifier applies to a moonrat's Strength and Intelligence scores while under the influence of moonlight. The size of this modifier depends on the amount of moonlight that reaches the moonrat, according to the table below. On a clear night, the moonlight equivalent is the same as the actual phase of the moon. On a night when clouds or heavy mist obscure the moon, the moonlight equivalent is one or two steps (DM's choice) lower on the table than the actual moon phase. On worlds with multiple moons, either choose only one moon to influence the moonrats, or estimate the moonlight equivalent of both moons on any given night, using the new moon and full moon entries as the minimum and maximum values, respectively, for that world.

Moonlight EquivalentLunar Modifier
New Moon+0

For every 2 points of Strength increase, a moonrat gains a +1 bonus on attack and damage rolls. The effect of the Intelligence boost is open to considerable DM interpretation. Use the Intelligence scores for the following creatures as benchmarks to determine the moonrats' increased intellectual capacity: Int 3 (minimum for a human), Int 6 (average for a gargoyle), Int 8 (average for a centaur or gnoll), Int 9 (average for an orc), Int 10 (average for a goblin). No extra skill points are gained for a lunar Intelligence boost.

Scent (Ex): A moonrat can detect approaching enemies, sniff out hidden foes, and track by sense of smell.

Uncanny Dodge (Ex): Because of its extraordinary sense of smell, a moonrat retains its Dexterity bonus to AC even when flat-footed, and it cannot be flanked.

Skills: A moonrat receives a +4 racial bonus on Hide and Move Silently checks and a +8 racial bonus on Balance checks. It uses its Dexterity modifier for Climb checks.

Moonrats fight just like normal rats do, biting and tearing with their teeth. Under the influence of lunar light, moonrats also gain the ability to organize, converse with one another, formulate complex plans, and operate complicated devices. Their leaders remember things done and learned nights or even months before. When the moon's light is at its peak, moonrats are capable of making and acting on long-range plans that may require dozens of full-moon nights to complete. These schemes are often so subtle and involved that casual observers do not connect incidents relating to a long-range moonrat plan until it is too late to stop it.