Brainstorm

Set Up

* The PCs are hired to investigate a strange magical barrier preventing further exploration in a gnomish mine.

* The PCs hear a rumor that gnome miners are being driven insane in the Abbor-Alz by a source of powerful evil magic. The rumor tells of great buried treasure in the area (elaborate as you see fit).

Adventure Primer

This is a weird adventure. It's set in the Abbor-Alz, but any relatively uncivilized hilly area will do (and no precise location is specified).

Centuries ago, a space-traveling illithid priest crashed in the area and was flung into a cave, out of his craft. Badly injured, his "life support system" took over and drew him deeper into the earth, to the place where he now lies. This "support system" cocooned him and kept him in stasis while his terrible wounds healed. Now, gnomes excavating a new ore vein have disturbed this cocoon, which has begun to grow and differentiate and bring the priest slowly back to consciousness.

The Brain-Cocoon

The PCs begin their adventure at point A on the map below, which shows the cocoon; the gnomes will fearfully bring them to this point. Think of the complex they're about to enter as a 20- foot-wide slice through a gigantic brain; inside, it's grey, gelatinous, slimy, and slippery (MV is half normal unless flying, etc.). A faint, peristaltic beating exists within it. To enter, the PCs must break through at point A. This first requires a successful dispel magic cast against 16th-level magic. That permits the PCs to negate a wall of force that otherwise bars their way to the outer membrane, at a distance of 5 feet.

The task for the PCs is to reach point D (the node), break through, and kill the mind flayer priest within chamber E. This is not going to be easy. At least some of the time, the PCs will have to destroy a "wall" section of the tissue here (at points A and D, and at least one point in between, whichever route they take). The "brain" will not take this lying down.

Innate Defenses of the Brain

The tissue of the brain can be affected by magical weapons or spells only. A 5-foot-wide by 5-foot-high wall section can be destroyed by inflicting 20 or more points of magical damage on it. When this is done, however, a magical effect is generated that is targeted at the PC who caused the damage (if more than one PC is involved, each will be affected by a separately-rolled effect). Roll 1d10 and consult the table below, and apply it to the offending PC. Add + 1 to the dice roll if the PC's attack caused 15 + points of damage, + 2 if it caused 20 + points of damage. Magic use by the brain is at 16th level. Normal saving throws against spell-like effects are permitted.

1d12	Spell Effect
1	weakness (reversed strength)
2	slow
3	enfeeblement
4	polymorph other (into small animal)
5	Evard's black tentacles
6	hold monster
7	invisible stalker attacks
8	enervation
9	flesh to stone
10	power word, stun
11	feeblemind
12	disintegrate

The brain structure negates spells that allow instant access to its core, such as passwall, dimension door, teleport, and the like. Likewise, spells that cause instant destruction of a swath of tissue (notably disintegrate) do not work here.

The brain has another line of defense. Each turn the PCs are within it, there is a 50% chance they are attacked by Id4 wandering (flying) giant amoebalike creatures that clean up the brain's structures. These attempt to destroy the PCs with sprays of acid (this doesn't harm the tissue of the brain). Amoebas have only enough internal acid for three sprays; they then use buffeting attacks.

Amoebas: AC 4; MV Fl 15 (C HD 5; hp 28 each; THACO 15/12 for ranged attack; if AT 1 (buffet or acid spray to range 20' Dmg Id4 (buffet) or ld8 + 8 (acid SD immune to mind-affecting spells, acid, electrical attacks, 25% magic resistance; AL N; SZ M (4' diameter ML 20.

Once the PCs have entered the brain node, point A reseals itself and now regenerates 20 hp/rd until the priest in area E is slain, making it almost impossible for PCs to escape until they have effected this!

Terrain: Unique

Total Party Levels: 80-85 (average 12th)

Specific Brain Locations

Node A is the entry node, where the PCs can gain access. Location B is the central ventricle of the brain, which contains a vast reservoir of an acid that harms humans or demihumans; if any area of ventricle wall is destroyed, acid gushes out to a range of 20 feet in all directions, inflicting 3d8 hp of damage. This effect lasts for 1 round, plus 1 round for every foot below "ceiling" level that the base of the damage is located. Thus, if a 5'x5' area is created at the very top of a ventricle wall (which stands 20 feet), acid gushes forth for 6 rounds; if at the base, for a full 21 rounds! Acid then runs along the ground in all directions at a rate of 10 feet per round away from the breach, to a maximum distance of 200 feet. Any PC standing in the stuff automatically suffers Id8 damage per round. Acid flowing along passages in this way filters away after 1 turn.[/p

Locations Cl and C2 are impenetrable barriers. Brain tissue here cannot be destroyed. It regenerates instantaneously (but the brain will attack any PCs who inflict damage). The only entry point now is the node at point D. This appears as a 5-foot-wide section of purplish-veined tissue with many fronds and tentaclelike projections. It requires 35 hp of magical damage to effect an opening here, and the area regenerates 5hp per round.

Within the central core, at area E, is the rising body of the illithid priest. It has two amoeba guards that attempt to block PCs getting at it, and the illithid itself attacks with mental blasts and spells, trying to evade melee if it can. The illithid appears to be a normal specimen, except that its torso is covered in a filamentous network of gluey strands; these improve its AC by —4, and anyone striking it with a weapon must make a saving throw versus wands or find the weapon stuck for Id4 rounds (a successful Strength check will release it).

Illithid Priest: AC 1; MV 12; HD 8 + 4; hp 67; THACO 11; #AT 4; Dmg special; SA mental blast, suggestion, charm monster/person, ESP, levitate, astral projection, plane shift; SD 90% magic resistance; AL LE; SZ M; ML 20.

Spells (as Prl2, but only combat-relevant spells are listed here): command (x2), darkness (x2), fear(x2), enthrall (x2),hold person (x3), continual darkness (x3), cloak of fear, obscure tongues, plane shift, true seeing.

Magical item: ring of spell storage with heal, maze, slow.

If the priest is destroyed, the brain loses all its magical properties, shrivels, and within Id6 hours, is nothing more than a series of pools of slimy, corrosive gunk.

Finally, within this central chamber, a weird, nodular excresence (sealed, takes 15 hp damage to break in) contains treasure: platinum-set moonstone rings and amulets with a few pearls and small diamonds set within them, worth 12,000 gp in total. The DM may consider adding a strange, alien magical item to this, which might have considerable magical powers and drawbacks also.

Developing the Adventure

The DM is encouraged to use his brain on this one! Specific areas of the main mantle of the brain might have special magical attacks/defenses linked to movement (motor cortex), perception (sensory cortex) and spell use by PCs (association cortex). By adding horizontal subdivisions, you can make this a 3D brain with sublevels. Reduce the number of amoeba encounters and damage sustained from hacking through the brain if the PCs have to cover longer distances.