How do you do this? Pick a list, roll a dice to see what you get, choose the default spell instead if you like and then choose another list or the same one again. You cannot have the same spell from the same list more than once per Wizard as normal, so re-roll duplicate results. However, you could have the same effect from two different spells, eg, Fire Ball and Dark Hand of Death.

Slann are so powerful that they add +1 to their attempts to both cast and dispel.