When I say 50% thats a 50% chance of them passing it themselves! Success is another issue entirely when someone is looking around for one.
EDIT: lol. Ah, editors. I just noticed that the Lictor is listed as having Size of mboth Hulking AND Enormous! I'm going to assume it's Hulking.
It doesn't matter. It's always an Opposed Test, and the opponent has a -30 due to the Lictor's special rule. Even if the opponent succeeds, he has to beat the Lictor's Degrees of Success, which have +2 added to them because the Lictor has Unnatural Agility x2.
Let's see, hmmm... A Lictor vs. a Space Marine with autosenses and Heightened Senses. Bog standard space marine has, say, Per of 40 and Awareness +0.
Lictor Ag40 Unnatural Agility (x2), Size Hulking. Concealment +20. So that's 40 + 20 = 60 -10 = a standard 50% chance BUT he gets 2 extra DoS on a success. (Also he gets another +10 if he's motionless but let's say he's moving around.). He has a 50% of succeeding and will get 2, 3, 4, 5, or 6 Degrees of Success.
Space Marine 40 + 10 (autosenses) + 10 (Heightened Senses) = 60 - 30 for Chameleonic Scales = 30%. He has a 30% chance of succeeding and will get 0, 1, or 2 Degrees of Success.
Tthe only way the Lictor won't win is if it fails and the marine succeeds (because the SM cannot beat the Lictor's Degrees of Success, no matter what the Lictor rolls, as long as it's 50 or less). The chance of which is... 50 x .3 = 15%. (BTW if the Lictor is motionless this becomes 40 x .3 = 12%.)
EDIT: Yeah, Ark of Lost Souls. The beasty in there has a number of Dodge/Parry Tests equal to its Agility Bonus, which I think is 10.
EDIT2. By eyeball math, I think that the highest possible Marine chance to succeed (Per 75 + Awareness +20 + Heightened Senses + Autosenses = 115 - 30 from Chameleonic Scales = 85%) will beat the Lictor only slightly more than half the time. If the Marine and Lictor both roll 50, Super Perceptive Marine will just barely win (by 1 Degree of Success).
Edited by bogi_khaosa, 15 January 2014 - 12:56 AM.