My house rules are based on the Mage 2nd edition rule set with one or two minor changes to account for the format (PBEM) and to cope with the pre/post Avatar Winds story arc.
As the game progresses I will be slowly changing some of the rules. This is to account for the gradual "tightening" of reality as the time of Mage Revised approaches.
I will, of course, give the players plenty of notice via the out of character mailing list, and will make the appropriate amendments in the House Rules pages.
Consider yourselves warned. ;-)
For magic, you roll 'arête', everything else is a 'stat + ability' roll (for example: 'dexterity + dodge', or 'intelligence + computer')
The exception, of course, is if the storyteller (i.e. me) specifically requests you to roll some strange combination.
A botch die is a die that results in a value of 1. Botch subtract from you successes. For example: Consider that you are rolling four dice at difficulty six and you get: 7, 1, 9, 4. There were two dice that returned six or more, but there was also one botch die, so you subtract on success (one per botch die). The result was one success (2-1=1).
Normally I will set the difficulty when I make a roll request, but if not then I leave it up to your judgment to determine the best difficulty.
Normally the difficulty will be six (the average). However there are things that can affect the difficulty, so check out the stats in the players are for a list of them.
An excellent success die is a die that results in a value of 10 (the opposite of a botch). Excellent dice do not add extra successes, rather they add the chance of more successes, in other words they add more dice to the roll. For example: Consider you are rolling four dice at difficulty six, you get: 4, 10, 5, 8. There are two dice that returned a value of six or more, but one of them was an excellent die, so you get one more die to roll (one extra die per excellent die). Let us assume that extra die returned: 3, which is less than six - so not an extra success. The result is two successes.
If the extra die had returned a 10, then it may be re-rolled too.
The extra rolls from excellent dice are made before deducting botch die. If an extra roll results in a 1 (a botch) then it deducts a success, just like a normal botch die.
After making the roll, the number of successes is equal to the number of dice that have a value that is greater or equal to the difficulty. For example: Imagine that you are rolling four dice, and the difficulty is six. You get: 5, 3, 6, and 9 from the roll. As there are two dice that got six or more (6 and 9), you got two successes from the roll.
Please note this result can be affected by botches and excellent successes.