I'm under the impression that you can always choose what unit is making the DtW roll when none of you units is targeted.
"To make a Deny the Witch test, first select one of your units that was a target of the enemy’s psychic power."
The only way you can choose a unit to make a DtW roll is if they have a psychic hood. You put a line through a very important part of the sentence.
I did a search for this on google and this forum was the first one I came a cross. I would like to add that on pg.26 it states that if none of your units were targeted by the enemy spell "...apply no modifiers to your dice rolls..."
That is a modifier so it cannot be used against all deny the witch rolls. The only thing I know of that applies to all deny the witch rolls is Khorne collars.
Hi and welcome to 40k online
I'm scratching the last part of the sentence for blessings, conjurations etc. Just like the rules says you should do.
"you can still attempt to Deny the Witch. To do so, follow the same process, but apply no modifiers to your dice rolls"
The part "To make a Deny the Witch test, first select one of your units" is still a part of the process, the scratched ("that was a target of the enemy’s psychic power.") part is not, as it is not required to have a target, hence the scratching of that part of the process.
Where do you find a modifier?
Is the specific rule "apply no modifier" a modifier? -No.
Is the re-roll from the runes of the farseer a modifier? -No.
Modifiers are explained on page 5 & 13, re-rolls are also on page 13.
If there is no modifier, it cannot not apply, neither can it apply, so the "apply no modifier" does not apply.
I hope that last sentence made sense.