Promethium Spur is an exotic which could possibly be better if it had more Subclass synergies. The first part of the exotic states that combatants and guardians beaten by Daybreak spawn healing/empowering rifts at their location. This is irrelevant on other subclasses. The second portion of the exotic states that solar weapon final blows will grant rift energy while standing in any rift. This part works on all subclasses. However, when rift energy is full on a non-Solar subclass, final blows do NOT spawn healing/empowering rifts. The exotic Arbor Warden for Titans have multi-subclass synergy with the void Bastion and the strand Drengr's Lash aspects. I think Promethium Spur would benefit from synergy like this with strand Weaver's Call, stasis' Frostpulse, and arc's Arc Soul aspects. Void's Child of the Old Gods and Final Shape's solar soul buddy should probably be spawned on the player. I feel the exotic needs a very slight tweak to rift duration or energy given from solar weapon kills. I think an extra 5-7 seconds to the combination rifts so you can run to them would be nice, as sometimes they can spawn far away from the player. Perhaps an extra 2 percent ability energy for solar weapon final kills would help as well? By adding subclass synergies, Promethium Spur gets gameplay similar to Nezarec's Sin, where you can choose to use weapons which do not synergize with your subclass in order to get other benefits.