Numion said:
Sneak attack works best from Imp. Invisibility or flanking; surprise round (or the round after it if you've got initiative too) doesn't really matter that much.
Except you just missed his entire point.
Improved Invis. means he has to rely on a spell, from another class, to use his ability effectively. An ability which is one of the major tenets of the class. Same deal with sneaking - if he has to rely on another person to cast spells on him to use major functions of his class, why even bother with the class?
Similar sort of thing with flanking. When it does come up, it means Wulf is right on the front lines, and an extra 1d6 damage (or is it 2d6, I forget how many Rogue levels Wulf has) at those levels isn't worth the levels put into Rogue. He'd have been better off taking levels of Ranger for the skills, and get some more fighting prowess out of it.
For the record, while Blindsight does say that creatures usually don't have to make Spot or Listen checks if you're in their range, as long as you know what kind of Blindsight they have and take measures against it, they should have to make a check. Blindsight though scent could be countered by rolling in the dirt or mud... maybe the first has them make a check with a +10 bonus, the second a normal check.
(Personal opinion)
Blindsight is a misnomer for the ability, I think. If it's just an alternative form of sight, they should still have to make checks. Hell, Dwarves don't automatically see anything within 60 feet of them when there's no light, why should something with echolocation? IMO Spot isn't just seeing stuff, it's interpretation of little things that are wrong - whether it's noticing that the bush over there just rustled and there's no wind, or there's a slight bump from the signal you received from that rock.
And on that note, why would something with scent-based Darkvision get a bonus to Listen? Maybe something with echolocation might, but something with vibration-based blindsight certainly shouldn't.
Of course, this argument is harder to make with something scent-based, but that's when you do something like I described above - don't make it a flat out success no matter what, but add a hefty bonus unless precautions are taken. A +20 bonus to a Spot check would suffice.
The more I think about this ability, the more recoculous I think it is. Maybe I'll write something up in House Rules about it.