[V3xx]

Say you had a squad that contained multiple psykers who had the Word of The Emperor power, and all of them were to cast it in the enemies assault phase, would the enemy have to take a leadership test for each time the spell is successfully cast or would they take one Ld test reguardless of how many times its cast?

 

[eiglepulper]

I would have to say that this sounds pretty much like the same situation as having multiple sniper rifles in a single unit. Even if more than one causes a wound, only a single Pinning Test is taken. To refer back to your psychic test question: the way I would play it is that only one Leadership test would be made since all the psykers with this power are bunched together in a single unit.

If they were in separate units then yes, there would be multiple Ld tests required as you would be resolving the results of several units including a psyker targetting the one enemy unit.

E.

 

[Red Archer]

No matter how many times the psychic power is used by one unit, the effects are that all units opting to charge the psykers or their unit has to pass a leadership test first. This requirement is fulfilled once one leadership test has been made and passed - for all Words of the Emperor that have been cast. It doesn't state that it stacks in any way, as such you gain nothing from casting it multiple times within the same unit.
(Same is true for other protective psychic powers. Force Dome grants you a 5+ invulnerable save. If you already have it you gain nothing from casting on the same unit with a second psyker.)

The power itself triggers no leadership test. It only forces a unit who wishes to assault the unit the power has been cast on to make a leadership test. Getting this one condition from several sources doesn't change anything.