"Yeah, it would be intensely unpleasant even in the best cases. Necromancy, to get this rounded out:"
Necromancy: seeing spirits and interacting with them! Plus working with corpses. There's still plenty of corpses involved. Being able to see spirits is rank-0 necromancy, which also lets you see the true form of disguised demons and some similar things. Most dead people pass on to an afterlife (usually some deity who claims them), but some stick around rather than get reaped, and witches can see those.
Rank 1 necromancy lets you make spirits visible to mortals or make spirits which hide from witches reveal themselves, and animate a few small relatively-intact animal corpses at a time, to act roughly as they would if alive. You can also contact a deceased spirit from its grave, though it may refuse to answer and you might get something unpleasant on the other end of the line instead. Rank 2 lets you take spirits you have managed to subdue and purify them, which restores their mind and can flag them for definite collection by a reaper. Most of a dozen dog-sized animal corpses are yours to reanimate, and you don't need them to be single-sourced as long as you have all the important parts from somewhere. Also, you can do elementalism-like tricks with bones, which improve from here.
Rank 3 lets you grab two dozen human-sized corpses, and if you convince a spirit to anchor to one of them, that one will stay animated if you lose focus on it or go to sleep. Also, use runework on bones if you like. Rank 4 lets you have nearly a hundred animated bodies, as big as whales if you can find (or make) the bodies. The fake animals will now be able to fly, swim, or do magical things they could do in life, even if the body doesn't really support that. Your bone-kinesis now extends to the living flesh and bone of anyone you want to make suffer, though this can be warded against pretty easily by witches. More pleasantly, you can cut out the middleman and directly send a subdued and purified spirit to the afterlife of your choice, though the divine proprietor may send them right back if they disagree.
"So, on that cheery note: Drawbacks next, or minor magic?"