In the Navis Primer expansion there is a renegade psyker power called Shielded by the Warp with the following description.
Shielded by the Warp
Value:
400 xp
Prerequisites: Desperate Transmogrification
Focus Power Time:
Half Action
Focus Power Test:
Willpower
Range:
Self
Sustained:
Yes
Those who become servants of the Warp may often look to the Warp to protect them. In a very real sense, the Warp may answer a psyker’s call, granting him some protection so that he may continue in his service to that entity.
The psyker may activate this power by making a Focus Power Test. If he succeeds, he shrouds himself in a Warp field that inflicts a penalty equal to his Psy Rating on any Weapon Skill or Ballistic Skill Tests for attacks directed at him. Any enemy who fails a Weapon Skill or Ballistic Skill Test when attacking a character protected by this power suffers 1 Insanity Point, plus an additional Insanity Point for every two Degrees of Success that the psyker scored on his Focus Power Test. The psyker may only take Move Actions while sustaining this Technique.
Only renegade psykers can use this ability, and from what the Navis Primer says, they'll have a Psy rating of 3. Max. Even with pushing that'll get them up to 7. A minus 7 isn't really that great for an ability that takes away your ability to attack. Am I reading that right? Do you think that's a good amount? If not do you have any idea for tweaks to make the ability more worthwhile?