Tiny beast, lawful evil
Armor Class 12
Hit Points 2 (1d4)
Speed 30 ft.
Proficiency Bonus +2
Proficiency Bonus +2 (5th Edition Advanced Mode)
| STR | DEX | CON | INT | WIS | CHA |
|---|---|---|---|---|---|
| 2 (-4) | 10 (+0) | 4 (-3) | 6 (-2) or variable* | 11 (+0) | 8 (-1) |
Skills (suggested) Perception +2, Stealth +2
Senses darkvision 30 ft., passive Perception 10
Languages telepathy 30 ft.
Languages (sugegsted) telepathy 10 ft. per intelligence point
Challenge 0 (10 XP)
Collective Mind (suggested). Every five rats in telepathic contact with each other increases the collective intelligence by 1 point to a maximum f 20.
Illumination. As a bonus action, the cranium rat can shed dim light from its brain in a 5-foot radius or extinguish the light.
Innate Spellcasting (suggested). The cranium rats’ innate spellcasting ability is Intelligence (spell save DC 8 + Intelligence modifier). It can innately cast the following spells, requiring no components and can cast each spell one per day per cranium rat present in the pack:
| Intelligence Score | *Spell-like Ability | # Cranium Rats |
| 1-6 | none | 5 or less |
| 7 | 1 level 1 spell | 6-10 |
| 8 | 2 level 1 spell | 11-15 |
| 9 | 3 level 1 spell | 16-20 |
| 10 | 4 level 1 spell | 21-25 |
| 11 | 1 level 2 spell, 4 level 1 spell | 26-30 |
| 12 | 2 level 2 spell, 4 level 1 spell | 31-35 |
| 13 | 3 level 2 spell, 4 level 1 spell | 36-40 |
| 14 | 4 level 2 spell, 4 level 1 spell | 41-45 |
| 15 | 1 level 3 4 level 2 spell, 4 level 1 spell | 46-50 |
| 16 | 2 level 3 4 level 2 spell, 4 level 1 spell | 51-55 |
| 17 | 3 level 3 4 level 2 spell, 4 level 1 spell | 56-60 |
| 18 | 4 level 3 4 level 2 spell, 4 level 1 spell | 61-65 |
| 19 | 4 level 3 4 level 2 spell, 4 level 1 spell, immunity to enchantment spells | 66-70 |
| 20 | 4 level 3 4 level 2 spell, 4 level 1 spell, immunity to enchantment and illusion spells | 71 or more |
Telepathic Shroud. The cranium rat is immune to any effect that would sense its emotions or read its thoughts, as well as to all divination spells.
ACTIONS
- Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 1 piercing damage.
5th Edition Advanced Mode
Limiting the power of a character and making the overall difficulty of the game harder, does not reduce the creativity, indeed it does quite the opposite.
The Game Master has the option to use any and all of the instances proposed in this guide, or just some of them according to their preference.
It is the lack of something that move and motivate characters, not the abundance of it
“Fear me. Fear my coming. What others know of me is a mask that hides my true might. They think I am vermin, those rats whose brains pulsate with bilious light. They do not know I see through the thousand eyes of my body. My body lives among them, and they do not see me
DESCRIPTION
A cranium rat is a small rodent with a grotesque appearance. Its fur is patchy and matted, and its eyes are dull and lifeless. The most striking feature of a cranium rat is its exposed brain, which glows with a faint purple light. The brain is the result of a mind flayer’s experiment, which imbued the rat with psionic energy and telepathy. A cranium rat can communicate with other cranium rats within 30 feet, forming a collective mind that grows more intelligent as more rats join it.
COMBAT
A cranium rat is not a formidable opponent on its own. It has weak physical abilities and only a simple bite attack. However, a cranium rat is rarely encountered alone. When a swarm of cranium rats forms, it gains access to powerful psionic abilities that resemble spells, such as confusion, dominate monster, or detect thoughts. A swarm of cranium rats can also use its telepathy to deceive or manipulate its enemies, or to coordinate its attacks with other swarms or mind flayers. A cranium rat can also use its brain as a source of illumination, shedding dim light in a 5-foot radius or extinguishing it at will. This can be useful for distracting or surprising foes, or for signaling allies.
HABITAT / SOCIETY
Cranium rats are usually found in the Underdark, where they serve as spies, scouts, or messengers for mind flayers. They can also be encountered in other dark and hidden places, such as sewers, dungeons, or ruins. Cranium rats are loyal to their mind flayer masters, but they also have a degree of autonomy and curiosity. They can sometimes act on their own interests or agendas, especially if they form large swarms with high intelligence. Cranium rats are not friendly to other creatures, and will often attack or avoid them unless ordered otherwise by their masters or their swarm.
ECOLOGY
Cranium rats are omnivorous scavengers that feed on whatever they can find. They have a preference for fresh meat, especially brains, which they believe enhance their psionic powers. Cranium rats reproduce by normal means, but they also inherit some of the psionic energy from their parents. A cranium rat swarm can grow indefinitely, as long as there is enough food and space to support it. Cranium rats have few natural predators, as most creatures are wary of their strange appearance and abilities. However, they are sometimes hunted by adventurers, drow, or other enemies of mind flayers who seek to disrupt their operations or learn their secrets.