Three is the Magic Number
Loitering to stare at the pebble perpetually falling down the supposed bottomless pit is not such a great idea. Shadows appear from the opposite walls! Not shadows cast by the flaming pebble, or whatever torch or magical light is illuminating the room, but shadows the incorporeal monsters.
The shadows approach and attack, ignoring armour as their insubstantial arms slash across our bodies. I'm not quite agile enough to avoid one of the attacks, causing me to feel my strength start to fade away as the shadow drains me.
'Mage armour still counts against touch attacks', both Brennan and Ganelon say, happily reminding me that Skelra's magic continues to keep me safe.
'In that case, the shadow's attack missed!'
'That's lucky', says the GM, 'as it just saved you six points of strength damage'.
'Good, because I kind of need that.' Fighting defensively helps again, giving me the +3 to armour class that contributed in preventing the attack from hitting.
'+2', Brennan reminds me. But, no, +3, because I have enough ranks in the acrobatic skill to provide a bonus to fighting defensively.
'Ah, I thought it sounded like an odd number.'
'That's because it 3 is an odd number', says Ganelon, happy to help where he can.