Sjonna and Her Voices
Sjonna is a weird little conlang. It's basically a big easter egg, designed not to look like so. It's also tripartite.
One of her peculiarities is grammatical voice. She has six voices, active, middle, passive, antipassive, reciprocal, and causative. This is achieved by gradation of the thematic vowel. This process is fairly regular, but there are some deviances. Let me showcase this by taking a perfectly regular verb and ablauting the shit out of it.
ACT: tētam
I destroy something. Active voice usually needs a patient.
MID: tātam
I destroy myself. Middle voice is usually reflexive when the single argument is in absolutive case. If the argument is in the ergative, it means I destroy for myself. Other verbs can change meaning completely in the middle voice (e.g. wējam I sing, wāje I mourn).
PAS: tītam
I was destroyed (by something). Passive voice doesn't really need a patient, but if the patient has to be referred, it is in a case that works like the ablative but has some peculiarities, hence I call it "receptive", while the agent is in absolutive.
AP: tūtam
I destroy (something). Antipassive, semantically, works exactly like the active voice. The patient needn't be referred at all (works better with verbs like "I eat", where what you eat is irrelevant to the discussion), because it's either irrelevant, mentioned once, or you want to put emphasis on the agent. If the agent must be referred, it has to be in the dative case, while the agent in absolutive.
RECP: tōtant
We destroy each-other. Reciprocal voice is most commonly used in dual or more. Since the nominal phrase(s) is both agent and patient, they are usually put in absolutive, though having both in ergative or accusative isn't uncommon.
CAU: tȳtam
I.ERG make someone.DAT destroy something.ACC. The causative voice is quite peculiar in Sjonna, for, depending on the case of the patient, the sentence can take a passive meaning: I.ERG am forced by-someone.REC to destroy something.ACC (REC here is reciprocal, same as above).