What penalties does Sensory Deprivation apply?

Question

Description of the ability:

The psyker has learned how to block the messages of the target’s senses. The psyker makes an Opposed Willpower Test against the target. If he succeeds, the target is struck deaf, blind, and is unable to scent or taste for as long as the psyker maintains the power plus 1d5 rounds. This power can also be used as a crude form of effective ‘invisibility’ allowing the psyker to pass unnoticed to sight or sound. The psyker selects a number of targets equal to his Willpower Bonus and selects which single sense he wishes to suppress. This must be the same sense for each target. Each target must make an Opposed Willpower Test. Those that fail notice nothing out of the ordinary, and the sensory information is successfully masked by the psyker until he stops maintaining the power.

Blinded penalties are well described:

A blind character automatically fails all tests based on vision and automatically fails all Ballistic Skill Tests. He also suffers a –30 penalty to Weapon Skill Tests andmost other tests that ordinarily benefit from vision.

As well as deafened penalties:

The character cannot hear at all, or at least not well enough to communicate with others. Until the character recovers or has his disability repaired, he automatically fails any Skill or Characteristic Test that relies on hearing. Apart from having trouble communicating with his fellow Explorers, the GM is free to decide what effects a deaf character will have on the game.

However, my players argued that when you are blinded you rely on hearing to make a task. For instance, a blinded explorer could still shoot in the general direction where fighting noises come. Hence, they say that the penalties of being both blinded and deafened should be way higher, and even incapacitating.

What penalties should I apply? Double the deafenead penalty? Make affected characters as good as incapacitated?

EDIT: Should I consider penalties based on the lack of smell and taste too? Maybe on animal NPCs?

Answer 1

Taking a quick glance at the RT Core Rulebook, I believe I have an answer for you for both uses of that spell.

The first use of that spell, if successful, cuts a single target off from most of their senses. They can no longer see, hear, smell, or taste (it is up to the GM whether that also takes away 'feel'). As the living creatures we are, we rely on our senses a lot more then even we sometimes realize until one of them is gone. Now imagine yourself without any of those senses at all. It would be a devastating experience, especially in a stressful and life threatening situation such as combat. However if you want to use strict rules on this subject, you could temporarily count the target's Perception score as 0:

0 Perception: The character is bereft of his senses and suffers a –30 penalty to all Tests (except Toughness) until he recovers. ~Rogue Trader Core Rulebook; Page 251

However given the situation, I would just count the target as Helpless or Unaware.

Helpless Targets: Weapon Skill Tests made to hit a sleeping, unconscious or otherwise helpless target automatically succeed. When rolling damage against such a target, roll twice and add the results. If one die rolled results in 10, there is a chance of Righteous Fury as normal, but if two dice come up as 10, a Righteous Fury is automatic (no second attack roll necessary). ~Rogue Trader Core Rulebook; Page 248

Unaware Targets: When a character has no idea that he about to be attacked, he is considered an Unaware target. Usually, this happens at the beginning of a combat when one or more characters are Surprised (see page 235). Weapon Skill or Ballistic Skill Tests made to attack Unaware targets are Easy (+30). ~Rogue Trader Core Rulebook; Page 249

Given the numerous amount of conditions being applied to it based on this one spell, I doubt they'd be able to do much except run in a randomly-generated direction once it got a hold of itself.

As for the second use of the spell, it is more subtle. It only masks either sight or hearing so the psyker has a better chance of getting by a number of targets equal to its Willpower Bonus.

In conclusion, yes I would agree with your players here. Most targets that are affected by this spell would be at a serious disadvantage on just about everything they can do and should be treated as such.