His build is something like Pech Rogue Burglar 7; 12 str, 19 dex, 14 con, 14 int, 12 wis, 11 cha; feats wolf pack basics/mastery/supremacy, knife basics/mastery/supremacy, ferocity basics (note: campaign property: fast feats). Skills +9 acrobatics, +11 athletics, +8 blend, +9 bluff, +12 craft, +1 disguise, +6 haggle, +1 impress, +1 intimidate, +5 investigation, +2 medicine, +11 notice, +14 prestidigitation, +12 resolve, +9 ride, +9 search, +9 sneak, +8 survival, +9 tactics.
The trick is, his character is going to be a glass cannon - it's something this player has done before, and often, so I know how it will likely go. He'll take down an NPC, and maybe one or two more, and do huge amounts of damage, and if they NPCs they are fighting are intelligent, they'll all gang up on the huge damage stabbing machine and take it down - and FC is way less forgiving than D&D4e.
I want to start off by saying this is a pretty good character as presented. Yes, he's got a big attack, but he's about as tough as you can expect a burglar to be, he's got *some* social ability and he's pretty good with out of combat utility.
I think in general the best answer is to let him win most of the time and throw the occasional nut he can't crack at him as long as everyone's having fun. When you need to smack him down, FC has plenty of ways. I've tried to list most of them below. Hope that helps.Negating sneak attack damage:
Construct, Elemental, and Plant types are immune to sneak attack.
Anyone with the Armor Supremacy feat while wearing armor (usually including Thick Hide) is immune.
NPC quality Damage Defiance (sneak attack) cuts sneak attack damage in half. Damage Resistance (sneak attack) will reduce his damage by its amount.
The usual vitals out of reach, no vitals, unable to clearly see vitals (flying, blindness, darkness, hidden, mirror image spell)Negating flank
Two Headed (giant, ogre) and Ebonscale (drake) species feats require 3 adjacent characters to be flanked.
Jungle crest species feat (saurians), Uncanny Dodge II (burglar, explorer level 8, or UD I twice), and the Elemental type can't be flanked at all.
The NPC quality Hive Mind can't be flanked unless all members of the hive mind are flanked.
Great swords, shields, and staves all have total defense tricks that requires a saving throw in order to move adjacent to the user.
Clubs and fencing blades have a stance that allows moving an adjacent opponent 5 foot. Following is optional.
Bull rushing can move (or sprawl) and is usable by everyone. It's not without its risks though.
The shove trick (usable by all melee and unarmed attacks) and the Qi Supremacy feat can move opponents away as well.Exploiting Wicked Stance (Knife Basics)Wicked stance requires a half action to enter and does not allow movement (except for 5 foot steps). Knocking him out of it removes 2 sneak attack dice (and thus 2 points of ferocity basics' damage)
Move. Let him set up and become immobile, then move the fight away from him. Works well with the anti-adjacency total defense tricks mentioned earlier.
Sprawling. Bull rushing, trips, and massive weapons mostly. Clubs have an AOE trip while great swords have a 10' AOE attack that can be used with a massive weapon. A minion with Whip Mastery can move him away from the boss and trip with a single attack.
Give the boss or a minion a reach weapon and the shove trick. When he's in stance, shove him twice. He'll have to drop stance and take a move action to become adjacent again. For hilarity, line some minions up with ready actions to shove him away from the boss. He'll go from glass cannon to hockey puck.