I have added Perception as a new ability score as described in "Notice Anything Different?" from Dragon Magazine #133.
The number of d6's rolled depends on the race and class selected. Everyone starts with a base roll of 4d6 and keeping the highest three. If you pick elf or half-elf as your race you may roll an additional d6, and if you pick thief, monk or ranger as a class you may roll another d6. You always only keep the three highest. So, if you are making a half-elf ranger you get to roll 6d6 keeping the three highest.
Bonuses/Penalties for Perception: Perception of 3 or 4 gives a -1 penalty to surprise while 17 and 18 give a +1 bonus to surprise. Rangers get a modifier to Tracking of 18=+2, 17=+1, 4=-1, and 3=-2. Thieves get a modifier to Detect Noise and Find Traps (but not remove traps) of 18=+10%, 17=+5%, 4=-5%, and 3=-10%.
Perception checks are handled by rolling a d20 (+/- modifiers) under your Perception stat.
3 days ago