Necromancy spells are absolutely strictly prohibited
As with druids, arcane spellcasters are expected to place the Three above their magic. Should it ever be deemed that an arcanist has put the art of magic above their worship of the Three, they face trial and punishment, possibly execution.
Once wizards reach a certain level of power (around 14th level in Pathfinder or 5e), they are watched very closely by servants of the Three to ensure they don’t aspire to more than they are permitted. This may even go so far as requiring that higher level wizards always be accompanied by one or more Inquisitors at all times.
One group of wizards known as the Order of Maylos
have been able to find a way to avoid their escorts.