spells can be cast multiple times until failed to cast, no other wizard may then attempt to cast it either, dispells dont stop recasts.
anything casting value 15+ can only be cast once per magic phase.
end time spells (all of which are 15+) CANNOT be dispelled if succesfully cast.
when attempting to cast a spell roll a d6, this is how many power dice you can use to cast it. EG. wanting to cast regrowth on a 12, you roll a 1 on your d6, you can only use 1 d6 plus your wizard level, therefore not being able to cast it, meaning you lose a minimum of that one dice you would have used plus you failed to cast it so no more attempts at it this magic phase by any of your wizards.
the same goes for dispells dice, roll 1 d6 and thats how many dice you can use to attempt to dispell something.
knowing just a single spell from any lore allows that wizard to know the entire lore.
lore master of any lore allows you to re-roll all spells attempts from spells in that lore cast by that wizard. (need to double check about if it allows you to reroll the number of casting dice, i dont think it does tho)
only level 3 or higher wizards may know the actual end times spells that they have options for.
think that covers the majority of it, enjoy
PS. all the rules are literally on the two pages in the khaine end times book, so those two page numbers lol