The Ectoplasm Master Alchemist Archetype
Instead of using alchemical reagents in order to create alchemical items (including his bombs, extracts, and mutagens), an ectoplasm master uses reagents such as corpse dust, crystallized ectoplasm, and similar reagents as alchemical catalysts. Just as with standard alchemists, the costs of these materials are insignificant and are comparable to the costs of the valueless material components of most spells.
As a result of his eccentric techniques and use of odd alchemical components, an ectoplasm master has an expanded formula list. He adds all sorcerer/wizard spells of 6th level or lower from the necromancy school to his alchemist formula list (but must still learn each of these spells normally). If a spell appears on both the alchemist formula list and the sorcerer/wizard spell list, the ectoplasm master uses the lower of the two spell levels listed for the spell.
This ability alters extracts and replaces Brew Potion.
So my question is, is that a good trade?
How much does the Alchemist rely on Brewing potions? What Necromancy spells are suddenly seriously worth considering?
An alchemist may get some mileage out of potions of enlarge or reduce person, or lesser restoration, but it's not a big deal. Nor are most necromancy spells because an alchemist can't cast spells on enemies, or on corpses to animate the dead. I guess there are a few useful defensive spells like false life.
The discovery which lets you summon creatures with the ectoplasmic template is much more interesting. If you're going to take this template that's the feature to focus on I think.