I surmised a possible system for wild magic recently, and made up a table for odd results of casting hold portal. I've been thinking along these lines a bit more, and decided, following smiler's suggestion, to tackle light, one of the least "sexy" spells of all time.
I'm quite pleased with the resulting table.
(See the previous post on wild magic for an explanation of the rough system I have in mind.)
01 The caster's eyes are targeted by the spell.
03 - Darkness manifests instead.
05 - The caster's hair or clothing sets on fire.
07 - A raging 8HD fire elemental is summoned.
09 + Spooky shadows of hooks, clawed hands and sinister spirits flit around the edge of the light's extent. One of them is a shadow (the monster) and will attack at an inopportune moment.
11 The light produced can be perceived by everyone except the caster.
13 - The caster is affected by faerie fire.
15 A sickening strobe light manifests, causing a -1 penalty to hit within its radius.
17 - The caster's eyes emit beams with equivalent intensity to the normal result, but highly directional.
19 - The light produced by the spell's whole normal duration is gathered and emitted instantaneously. All within 60' must save versus spells or be blinded for 1d6 turns. If the save fails by more than 4 the blindness is permanent.
21 + Spooky shadows of hooks, clawed hands and sinister spirits flit around the edge of the light's extent.
23 - A floating silver lantern appears, burning with an ethereal light. The caster can move the lantern telekinetically.
25 - The caster is covered with a thin film of luminescent ectoplasm. Everything he touches gains a glowing residue. This includes his footprints as he walks around.
27 - No light is produced, but objects and creatures in shadows within 60' of the caster are annotated with neon signs denoting their identities. This effect moves with the caster.
29 - A hundred candles appear at the specified location. They burn for the normal duration, but can be blown out.
31 + The created light has an unusual additional property – it absorbs other nearby light sources. Any light source within 30' is extinguished. Each time this happens the radius of the magical light increases by 5'.
33 - The caster is transformed into a globe of light, having the normal effects of the spell.
35 + The light sends off small sparks which gradually form streams leading towards the centre. This attracts wandering monsters (chances double).
37 - A defective light manifests, which is “on” every two rounds, and produces darkness instead every other round.
39 - A brief flash is emitted and a photograph of the scene drops at the caster's feet.
41 - Sound within 60' of the caster is silenced and instead manifests as glowing shapes, colours and images. This includes the caster's own voice. Spell casting is still possible, but speech must be interpreted visually.
43 - A backwards light is produced, which reverses the apparent location of objects. Things which are behind the caster appear to be in front of him, and vice versa.
45 + The light produced is completely invisible from outside its radius.
47 - All living creatures within 60' of the caster are illuminated as if by a spotlight. The effect follows them as they move.
49 - A color spray shoots in all directions from the caster.
51 The light only illuminates the edges of things, revealing outlines without colour or texture.
53 - If underground, the caster and companions are teleported to the surface. If above ground, a meteorite (as per meteor swarm) plummets from the sky and hits a random target within 60'.
55 - The light forms a wide beam 60' long, which rotates around the subject like a lighthouse beacon.
57 The light produced is of an unusual colour such as sickly violet, gloomy red, electric blue, etc.
58 - A torch-bearer (1HD, AC9, unarmed) is summoned, complete with torch which burns magically for the normal duration.
61 + A switch appears floating in front of the caster, and following him as he moves. The switch can be used to instantaneously switch the light effect on and off.
63 The light produced can only be perceived by the caster.
65 - A swarm of fireflies is summoned. A reaction roll determines if they fly off in random direction, swarm around the caster, or obey the caster's commands. The swarm sheds light as the normal spell effect.
67 - The caster is transformed into a holographic being made of pure light. He can no longer directly interact with the physical world, and is unable to speak, but can only be harmed by magic, and can pass through tiny cracks and holes.
69 - An odd light is produced which only illuminates certain things: 1. living beings, 2. invisible things, 3. magic and enchanted items, 4. evil intent, 5. treasure, 6. undead.
71 + The light is augmented by flashing neon-style arrows and slogans of an encouraging, whimsical or helpful nature. (“This way!”, “You're doing great!”, “Look out!”, etc.)
73 - A will-o'-wisp appears.
75 + The light is centred on the caster, who is also affected by invisibility. The caster thus becomes a walking light source.
77 - The spell conjures an elegant standard lamp, with electric cable plugged in in another dimension. The caster can carry the lamp around.
79 - All creatures within range are affected by faerie fire.
81 + The light flashes briefly whenever a creature crosses its boundary.
83 Ultraviolet light only, just like at a rave. Anyone staying in the area of effect for more than an hour will get a tan.
85 + The light is also very hot, causing anyone in its area of effect to start sweating within 1 turn. Heavily armoured characters suffer -1 to hit, due to the heat.
87 - The caster gains the ability to see in darkness.
89 + The light produced has the unusual property of exerting a physical force which can push away objects and creatures. A save vs paralysis is required per round to remain within the illuminated area.
91 + Twisted images of the caster's face dance at the edge of the light's extent.
93 - All creatures within 30' gain the ability to see in darkness.
95 - A scintillating array of blue laser beams emanates from the target, illuminating the normal area. If the target is an object which the caster holds, he can command it to fire intensified beams of laser energy, causing 1d8 damage on a successful hit roll.
97 - Spell's effect replaced by continual light.
99 - The eyes of all beings within range are targeted by a normal light spell.