Infravision

       Usage: cast 'infravision' <target> : cast 46 <target>
      Effect: Explained below.
        Cost: 40
    Duration: 12 + level hours
Casting Time: 12
      Target: One MOB or character

When cast, this spell will give the recipient the ability to see players
or MOBs in the room through their heat, needing no light.  It will not
allow them to see room descriptions, items or exits.

The classes that get the spell infravision are:

magic-user : Level  13 (good)
cleric     : Level  53 (good)
priest     : Level  43 (excellent)
bard       : Level  73 (average)
darknight  : Level  38 (average)
wizard     : Level  18 (excellent)
druid      : Level  32 (excellent)
ranger     : Level  20 (excellent)
illusionist: Level  21 (good)