Magic

In my regular group we have been using Arcane Stress for a while now. I guess since 2011. Yikes.
It works great and does what I want it to do, which is make magic a bit more powerful, weird, and dangerous while changing as little as possible of the regular BX Vancian magic system. The way it works is Magic-Users cast spells just like they normally would in your old school system of choice. If the want to cast any more than they normally would be able to, they can try but they've got to roll a D6 on this table:

1d6	Spell result:
1	Fails. Caster is knocked out d4 turns.
2	Fails.
3	Mutation. Roll on the Spell Mutation Table.
4	Cast at ½ strength.
5	Cast. M-U ages d6 months per spell level.
6	Cast at x2 strength. M-U looses d4 HP per spell level.

Actually some where along the line in the hardcopy I use in game I penciled in some changes:

1d6	Spell result:
1	Fails. Caster is knocked out d4 turns.
2-3	M-U is embroiled in a mystical melee with unseen forces. Roll again next turn.
4-5	Mutation. Roll on the Spell Mutation Table.
6	Cast at x2 strength. M-U looses d4 HP per spell level.

This system is fun because in truly dire situations Magic-Users can take action (magic flavored action) and it might make things worse or it might spectacularly save the day. I changed the table to make mutations more common (because they're fun) but I think the whole idea could be tweaked to be more fun. In my group, when a wizard casts via Arcane Stress it pretty reliably makes the situation entertaining because it is so dangerous/random, but really it is a rarely used last resort.

I feel like it could be changed to make magic more powerful, weird, and dangerous. I've been thinking about this lately because of Brendan's post on Catastrophe Magic. This is a pretty slick roll to cast system. This takes us a bit further from Vancian magic, but it does more to make magic chaotic and interesting without making too much extra work for the player or the DM.

	13	11	9	5	3	1	*	*	*	*
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1

The left hand column is the D20 roll.

The top row is the level of the caster.  

The results break down like this:

	Principal Intensified
	Principal
	Principal and Corollary
	Corollary, Decline and Delay
	Catastrophe

Those are all per Brendan’s descriptions except “Corollary, Decline and Delay” which is corollary and decline plus the spell will go off at the end of the following turn.  After a “Corollary, Decline and Delay” is rolled the MU moves to the next column the next time a spell is cast.  

I’m going to think about this more but I think it could add a bit of interest and make casting get increasingly risky which sounds fun.

WHAT HAPPENS WHEN SOMEONE TRIES TO READ A WIZARD’S SPELL BOOK:

WHAT HAPPENS WHEN SOMEONE TRIES TO READ A WIZARD’S SPELL BOOK:		AND IF THE READER IS ALSO A WIZARD AND CASTS READ MAGIC:
1	They don’t. The thing is locked. The thing is tight. There is no visible lock for the thief to pick. Not even Jimbo the fighter can even pick the thing up.	It grows D6+1 demonic chicken legs and runs away. (In the direction of the Wizard who owns it)
2	An uproarious stream of light and sound erupts from every page if the book is opened. (Make a wandering monster check every time this happens)	Anyone nearby who makes a saving throw suffers D6+1 damage and anyone who doesn’t’ is knocked out. Effects continue each round until the book is closed.
3	It’s just page after page of complete gibberish… Wait, here is something that you can make out. Do you read it? (See table below)	(See table below)
4	The arcane symbols are difficult to make out. Out of the corner of the Reader’s eye they make out a figure. If they look directly at it, it is gone. If they look away again they will see the figure walking towards them out of the corner of their eye. If the figure reaches them it will strike with a dagger each round and automatically hit. By looking at it the reader can make it disappear. Only by focusing their gaze on the last place the saw it and backing away can the Reader make it stop. If they take the Spell Book it follows.	They may make a Saving Throw to avoid the effects described to the left. If the Reader continues to attempt to read they must save again.
5	The words on the pages crawl up the Reader’s arms and into their mouth, where they transform into an unending string of the most foul and blasphemous uncontrollable utterances. By stripping naked and scraping off the words crawling on their skin and physically plucking the words from their tongue the effects can be ceased.	Instead of blasphemies random spells are uttered.
6	Nothing, they can’t read magic.	The spells therein may be deciphered.

IF THEY READ THE LEGIBLE TEXT HIDDEN AMONG THE GIBBERISH:
(if the Reader casts Read Magic they can make a Saving Throw to avoid the effects described below)
1	The Reader is turned into a toad.
2	The Reader is turned into a slimy mass of tentacles and mouths.
3	The Wizard who owns the Spell Book instantly appears.
4	The Reader and anyone nearby is teleported to the current location of the Wizard who owns the spell book.
5	They cast Geas on themselves and are compelled to return the book to it’s Owner.
6	As 5 above, but it affects everyone in the room and it’s a competition. Each person or creature wants to be the one to return the book to its Owner.