Personally I'd like to see all the suggestions I am going to make implemented but would be happy for anything.

1) Make it so that it can not be placed in combat.

2) Make it so that it does not work in revealing rangers. (Explaination below.)

3) Give it a wear off timer in the assassins affects list.

4) Make it increase the assassins stealth abilities against the marked target in that they can hide so well that they are effectively duo in civilized environments against their target only.

5) Give it a save based upon a comparison between the assassins int and wis vs the targets int and wis and the differential between the civilized/wilderness time of the two opponents.

6) Make Locate mark a togglable skill that automatically gives updates on the mark and deducts coinage when ever the assassin enters his guild.

About #2 The reason I would like to see mark not work in wilderness is for a few reasons. Given that it can be used in conjunction with "Locate Mark" to locate marked targets suggests that it is a mark that only the secret society of assassins can detect and is thus something rooted in networks and society. I find myself struggling to see the justification that a streetwise killer is able to head to Yellowstone National Park and hunt down and kill a Delta sniper because he has a mundane method of seeing the unseeable. I'm okay with the bonus remaining for disarming and for the mark retaining it's potency vs the ranger in other areas, especially what I listed above. (Disarming and locating in cities)

Assassins have so many tools for fighting rangers(And every other class) already that I feel they don't need to be able to nullify the rangers biggest offensive move and defensive ability with a 10th level skill. Perhaps allow the ranger/Outie to camouflage but not ambush.

My most PK successful character was a Dark-elven assassin that more or less feasted on rangers in their natural habitat. Enough so that I was able to gather a couple edges from PK's alone. That's huge for me!

The skill just seems magical to me. Certainly more powerful than it should be on a class that's already amazing in all arenas.