| Tiny Magical Beast |
| Hit Dice: | ½d10+1 (3 hp) |
| Initiative: | +2 (Dex) |
| Speed: | 40 ft., climb 15 ft. |
| Armor Class: | 14 (+2 size, +2 Dex) |
| Base Attack/Grapple: | 0 |
| Attack: | 0 |
| Full Attack: | Bite +4 melee |
| Space/Reach: | 2½ ft. by 2½ ft./0 ft. |
| Special Attacks: | Mental powers |
| Special Qualities: | Communal defenses, hive mind, scent |
| Saves: | Fort +3, Ref +4, Will +1 |
| Abilities: | Str 2, Dex 15, Con 12, Int 2+, Wis 12, Cha 2+ |
| Skills: | Balance +10, Climb +4, Hide +14, Move Silently +6 |
| Feats: | Weapon Finesse (bite) |
| |
| Environment: | Any underground |
| Organization: | Swarm (10-100) |
| Challenge Rating: | 1/8 per rat; +1 CR for every ten rats above 34. |
| Treasure: | None |
| Alignment: | Neutral Evil |
| Advancement: | - |
| Level Adjustment: | 0 |
Cranium rats are verminous creatures not uncommon in Sigil and pestilent cities of the Lower Planes. Cranium rats are distinguishable from their normal cousins by the pulsating brains that protrude from the tops of their skulls. They are many creatures and one all at once, for they possess a type of group mind. Cranium rats exist as the eyes and ears of Ilsensine, the great god-brain of the illithids. The extent and purpose of their powers are held closely secret, lest Ilsensine's instruments be discovered. Those who discover the true purpose of the cranium rats are undersentance of swift and terrible death.
CombatThe cranium rat is not an aggressive creature, avoiding open attacks in favour of flight or ambushes. Cranium rats usually move in swarms of ten or more.Communal Defenses (Su): When calculating damage from area-affecting spells, the cranium rat swarm is treated as a single creature with one pool of hit points. For example, a fireball that inflicts 20 points of damage kills of 20 hit points of cranium rats, rather than all of them.Hive Mind (Ex): Cranium rats are automatically in telepathic contact with all other cranium rats within 10 fet, and possess a group mind that allows them to share not just thoughts, but also brain capacity - every five rats in contact generate 1 point of Intelligence and Charisma, and grant a +1 bonus to all saving throws. However, the rats quickly break the telepathic link with any individual that falls under another creature's control. Consequently, spells such as suggestion and charm monster affect but a single rat.Mental Powers: With increasing Intelligence comes increasing powers, as shown below. These powers are cumulative.
| # Rats | Int/Cha | Abilities |
| 1-4 | 1None |
| 5-34 | 2-6 | None |
| 35-39 | 7 | 1 level of sorcerer spells |
| 40-44 | 8 | +1 level of sorcerer spells |
| 45-49 | 9 | Mind Blast, 1/3 rounds |
| 50-54 | 10 | +1 levels of sorcerer spells |
| 55-59 | 11 | +1 levels of sorcerer spells |
| 60-64 | 12 | Mind Blast, 1/2 rounds |
| 65-69 | 13 | +1 levels of sorcerer spells |
| 70-74 | 14 | +1 levels of sorcerer spells |
| 75-79 | 15 | Mind Blast 1/round |
| 80-84 | 16 | Immune to gases |
| 85-89 | 17 | Immune to cold |
| 90-94 | 18 | SR 13 |
| 95-99 | 19 | SR 19 |
| 100+ | 20 | SR 25 |
Sorcerer Spells (Sp): Cranium rats can cast a number of spell-levels of sorcerer spells each day; for example, a 55-rat swarm might cast two 2nd-level spells, one 3rd-level and one 1st level spell, or one 4th-level spell each day. The cranium rat swarm casts these spells at a level equal to half its Intelligence score. The save DC of these spells is 10 + the spell level + the swarm's Charisma modifier.Mind Blast (Sp): This attack is a cone 60 feet long. Anyone caught in this cone must succeed at a Will save or be stunned for 3d4 rounds. The DC of this saving throw is 10 + ½ the swarm's Intelligence score + the swarm's Charisma modifier.Skills: Cranium rats receive a +4 racial bonus to Hide and Move Silently checks and a +8 racial bonus to Balance checks. They use their Dexterity modifier for Climb checks.Habitat/SocietyNone0EcologyNone
