Tuesday Trap #4

Yeah, I know it's Thursday, but I've decided that I'm actually going to catch up on the traps I missed. So you get a Tuesday Trap today.

My Rolls:
10: Melee Attack
20: Touch Trigger (magical)
15: Blade Slash
12: THAC0 14 (+6 to hit)
9: 2d6 Damage

Trigger: Touch (magical)
Save: AC
Reset: Automatic
Effects: None
Duration: Instant
Bypass: Larger steps, clogging

Description: Of a set of stairs, one or more of them is trapped. When a trapped stair is touched, no matter how lightly, a blade swings out from below the stair one step higher. The touch and the magic involved power the swinging blade, so no reset is required. The blade hits at +6 and only the character's armor protecting the shins or calves (depending on whether the character was ascending or descending) counts towards calculating AC for the attack. The blade does 2d6 damage and may cripple characters at your option (characters may, again, at your option, get a saving throw to mitigate or avoid crippling). Characters should make a saving roll not to fall, taking whatever damage is appropriate. Cruel referees will place multiple traps on the same stairway and/or have this stairway run along a drop-off for increased damage from falling.

Detection/Disarming: The simplest way to detect this trap is to tap each stair with a pole or other object before stepping on it; amusingly, even players who think to do this on a dungeon level's floor will often not check stairs before descending or ascending them. Once detected, taking a larger-than-usual step is sufficient to avoid the trap (unless the next stair is also trapped…). The small slot the blade emerges from should be camouflaged, perhaps by a dark strip of cloth that hangs over it and blends in with the stair, or another method of your choosing; visual detection should be difficult. Detect Magic will also detect that something is magical about the stair, but will not indicate anything about the blade; the magic portion of the trap is wholly contained in the stair. This trap may be jammed or broken by roughly and forcibly inserting items such as poles or crowbars into the trap.