Stop mutation in Sindarin
This one is also never mentioned in Tolkien’s official writings on Sindarin. A mutation by this name is mentioned in his Gnomish Lexicon. It is not very well attested, most of what is recorded here is extrapolated from what little is known. That being said, the following words trigger stop mutation:
o (=from, of), preposition, it is possible to change ‘o’ to ‘od’ before vowels, but this is not necessary. This would probably be done in cases like ‘od orch’ (of an orc), to avoid the double o (‘o orch’). On the Moria gate inscription ‘o Imladris’ is written, though ‘od Imladris’ would apparently also be possible.
ed (=out, out of), preposition, mostly shortened to ‘e’, see the table for details.
ned (=in), preposition, behaves like ‘ed’, however, it would probably not become ‘nef’ to avoid confusion with ‘nef’ (=on the side of).
Now, the table with the mutations:
Ps. The ‘es, ef, eth’ (as well as ‘nes’ and ‘neth’) were “often found”, according to Tolkien. This means that the other forms are also possible.
