Oh just for more info, I looked at patching it at a lower level but they didn't really seem relevant. More like UI stuff that didn't need patched?

(Obviously you can't see the uses of cellRect = from this screenshot, but I investigated them.)
Interesting to see that though CellRect has many methods, many of which return bools, I (think) I only see .Contains used for CurrentViewRect... which makes sense.

If you think about it, to ensure determinism, a method like IsValidUnseenCell can't ever return true in MP. The methods you patch either check the camera rect or Find.CurrentMap both of which are allowed to vary in multiplayer so these methods should just get a destructive prefix to always return false I think.

This will drastically affect the event though so I'll have to play around with it to decide how to handle it.

I forgot about Find.CurrentMap 😅

I think they're just combining tests of "validity" for the event but also "unseen" for spookiness. More like IsValidAndIsUnseen(). I think I can just patch out the map part also. They just don't want the player to "see" it teleport, but who cares. I think these are only used here. I can give it another go and report back. 👍

Updated and tested in-game. Corpse teleports around now like it should.

Here's a diff of the before and after opcodes.
https://gist.github.com/CodeOptimist/454832f119239fbf3e8e4d4c6098a98e/revisions
(I was really hoping it would embed that link. I'm a little disappointed.)
(The diff is misaligned slightly; obviously patch adds lines 32 & 33, not 33 & 34.)

Thinking about this code again, I think only one patch would be enough, either to CellRect.Contains or Find.CurrentMap check. The condition in both cases could be simplified as (isTargetValid) && (map != Find.CurrentMap || !CellRect.Contains(target)).

We obviously cannot change the first part of the code, since this could likely introduce bugs (and same could be said about making a prefix to always return true). However, patching the second part would require changing at least one of the 2 conditions, as only 1 of them needs to be true (and this PR patches both).

Now, it is more of an observation I've made looking through some of the PRs that are both active or were merged. I'm wondering if we should keep both patches, or should we keep only the simpler of the 2?