Dark field

The area around the caster is plunged into darkness. Darkvision has no effect here. The caster may designate up to four creatures including themselves to be able to see within the field. Spells that auto target like magic missile will fail to find their target if they enter the dark field, instead targeting the closest creature that does not require it to touch the field to reach. 

Any attacks made within the field count as sneak attacks. (Attacks do not count as sneak attacks if the attack is directed towards a creature that can see within the field)