So, I see how the mod team is thinking here. They want to make the Dead Marshes dangerous to traverse, like they were for Frodo and Sam, but having "trances" would be annoying, and do little hurt to the player.
I am suggesting that they are changed to do that sort of "trances" thing, but with a few others:
So, you go into the Dead Marshes. Be sure not to stare at any water block for too long! If you do this for 10 seconds, you will become "entranced", and will be controlled to walk into a pool. (The pools will be deeper if this is endorsed.) Likely it is, that they will drown. (I know that it may be hard to control a player's keyboard and mouse with code, but just TP the player one pixel or so toward where they stared. Be sure to force them to keep staring that way!) Also, this may seem to not have to do with the Marsh-wraiths, but they come in here.
So when the player is being "entranced" and forced to move toward the block they stared at, a Marsh-wraith will appear. They will stand above the "anchor block" (the block the player stared at) and seem to beckon for the player to come.
When they get near, the Marsh-wraith will back so the player does not go through the Marsh-wraith. (Marsh-wraiths will still appear inactively in the Dead Marshes, appearing and disappearing as they seem to will.) The player will certainly fall with their head in water. Because of the Marsh-wraith's presence, the player will drown much faster than usual. If the player struggles, it makes the time it takes to drown increase, making struggling a great way to waste time. (Yes, it can increase to more than usual (vanilla) drown times!) When the player drowns, a Marsh-wraith will spawn in their death-place in an inactive state, and the one that beckoned will disappear. The player's wraith will appear to have the player's head, but very much lighter to the point where it is difficult to tell. This "Player Wraith" will never move, but will rise when the player it is comes by. After encountering your own wraith, you are lucky that it will disappear, doing ten damage points (five "hearts") as it leaves. This head suggestion is an extra, and is not necessary. Also, whenever a wraith appears (player or default), it will play the Barrow-wight spawning sound. When a wraith (also player or default) disappears, it will play a screaming sound.