I'm not going to comment on time here but Nightfalls (As it stands in week 2) have burns on them. The prism mechanic is a rotating burn where players will do more damage and receive more damage from the current element that is active. Look for the 'X energy surrounds you.' message in the lower left hand corner of your screen just above your super bar. This will also reduce the damage of the other two types both on enemies and against you. While the burn may not seem as much as in D1 the damage is significant and with sufficient coordination optimal DPS can occur.