Nagash knows all spells?

[Ellisrich]

I’m new to age of Sigmar and was looking at Nagash’s wars roll which states that he knows all the spells of death wizards on the table, both friendly and enemy.

But does Nagash forget the spell once another wizard is slain, off the table, or if using the ageless cunning ability from legion of night, would Nagash only know the spells of wizards once they have appeared? 

[King Taloren]

No he knows all the spells available for the duration of the battle so even if a wizard dies he can still use those spells.

I guess there might need to be an faq about when a wizard comes to the table during the game but I would guess he knows those spells as well.

[Ellisrich]

That’s what I was thinking thanks 

[Fluttershy]

2 hours ago, King Taloren said:

No he knows all the spells available for the duration of the battle so even if a wizard dies he can still use those spells.

I don't think so.

"[..] any spells known by other Death Wizards on the battlefield."