I'm new to Pathfinder, and I've been putting together a build for a Tiefling rogue. I'm wondering what happens if I use a wand of darkness (or the Tiefling racial ability) to cast darkness on my pants at the start of combat. It seems like I should then have total concealment for the next several rounds (assuming a dim-light environment). Can I then make full attacks to fire a bow, throw daggers, or melee from this darkness, and have them all count as sneak attacks?
RAW: yes, but under some additional conditionals.
RAI: maybe in conjunction with the stealth skill.
The darkness spell & the tiefling ability change the lighting conditions magically by lowering it by one step. Mechanically this can grant 'concealment' (in dim-light) or 'total-concealment' (in darkness).
Sneak attack triggers off of 2 conditions: When your opponent is denied tier DEX bonus to AC or while you are flanking. (Neither of those conditions are directly cited in the darkness spell).
However, The lighting and vision rules state (emphasis mine):
So, if the creature you are trying to sneak attack is inside your magical darkness and does not have darkvision, then you can sneak attack them. Otherwise, your trick will not work RAW.
Note: However, while you have concealment you can usually use stealth, which by some RAI discussions on the 'new' stealth errata, can give you some reasonable arguments for house rules that would argue for allowing sneak attack from a concealed/hidden position.
The Darkness spell drops the lighting level by 1 stage. So if it were cast in normal light, you would have a 20% miss chance against creatures that lack darkvision. If it were cast in an area of already dim light, the lighting would drop to darkness, which would grant you total concealment. This grants you a 50% miss chance, but also does not deny them their dex bonus to AC. However, in areas of darkness, creatures without darkvision gain the blinded condition which reduces their AC by 2, denies them the their dex bonus to ac, and applies a -4 penalty to strength and dexterity checks.
So, IF the lighting is already dim, AND they lack darkvision, then casting your darkness SLA will let you make sneak attacks.
See here for the rules on darkness granting the blinded condition:
The darkness spell will reduce dim light to darkness. Darkness blinds creatures without darkvision which denies them their Dex bonus to AC, which opens them up to sneak attack. But a ranged attack from within the darkness at a target outside would not deny them their Dex bonus and thus not be eligible for sneak attack.