Sneak Attack Question

[doseyclwn]

What cannot be sneak attacked? I'm not sure I understand the conditions that do or don't allow for this. Can undead or incorporeal creatures be sneak-attacked?

[LordEntrails]

Yes, unless something has an ability that says they can not be sneak attacked, then they can. Don't try to think about 3/3.5/PFS rules applying to 5E, they don't :)

[Zacchaeus]

There are only two basic conditions; first you need to have advantage on your attack roll - if you do then you get to add sneak attack damage to the damage roll.
Second; if one of your allies (who isn't incapacitated) is within 5 feet of your target then you get to add sneak attack damage if you hit. You don't need to have advantage on the attack roll if this condition is fulfilled.
You don't need to meet any other conditions - at all.

[spite]

It's worth noting it has been said by Mearls and Crawford that the rogue is balanced around the rogue ALWAYS attacking with sneak attack, so don't try to take it off of the rogue with house rules because you may have liked how old versions did it. It's all the rogue has!