I spent 2 and a half hours last night trying to make a Templar Caster build work on the Craglorn Shadow boss with only 6 people in the group. This meant DPS was slow enough to get a good feel how this build will perform.

I tried the following loadouts (all with Inner Light, 5 piece VR12 Martial knowledge):

1) Entropy (Might of the Guild proc)
Vampire's Bane
Dark Flare
Power of the Light

2) Unstable Wall of the Elements
Vampire's Bane
Entropy
Power of the Light

3)Vampire's Bane
Spear Shards
Puncturing Sweep
Power of the Light

4) Vampire's Bane
Power of the Light
Spear Shards

5) Vampire's Bane
Spear Shards
Puncturing Sweep
Unstable Wall (Entropy tested here for 2 kills)

Keep in mind, I am not specced for flawless dawnbreaker, because like almost every other templar I am set up to tank and heal, light armor/heavy armor

On the 4 spell rotations, you can fit 2 heavy attacks in after applying UW, VB, Entropy following Power of the Light, aside from example 3 where Puncturing Sweep was used as filler. Unsurprisingly, this one left you magicka-starved and didn't do great damage due to how PS doesn't scale off spell crit.

On the 3 spell, you can fit 3 heavy attacks into each POL window maintaining heavy uptime. I am average to subpar at animation cancelling, but I am going to give you numbers based on the times where I feel I nailed it perfectly. My primary focus was always on keeping Power of the Light up.

I was able to get 5-7 POL's off on each kill, with the 4 spell rotation being closer to 5 and the 3 spell being at 7 nearly every time. I could sometimes get a sixth to proc prior to the death on the four spell.

Rotation 1 Avg. DPS (across 8 kills)
399

Rotation 2 Avg. DPS (across 8 kills)
487

Rotation 3 Avg. DPS (across 8 kills)
427

Rotation 4 Avg. DPS (across 8 kills)
502

I viewed rotation 5 as a test group, and indeed, its dps was more than 100 off the POTL experiment groups. As such, I only used it for 5 kills.

I've established the following:

1) Dark Flare is a DPS loss due to the cast time. It simply is. Working it into the rotation killed DPS nor did it do anywhere near enough damage for the magicka cost on crits. It's other morph is a waste, as well. Even as melee, it is simply always better to cast Spear Shards. Elemental Ring blows Solar Barrage out of the water for AoE, too.

2) Puncturing sweep's DPM is not really that great. It's understandable based upon its self-healing, AoE, and knockback components. The animation is really a loser, too.

3) Vampire's Bane, in and of itself, isn't a bad spell. The DPM is solid. The animation and travel time are putrid, though. They literally lower DPS because your toon's arm raises and casts as slowly as the projectile moves. It's like watching paint dry.

4) Spear Shards not moving with a target sucks. The ability itself is amazing. However, Burning Light's proc rate has no scaling modifier (it should go off your spell crit with say, a 50% base as is the case now.) It produces the largest swings, as well. The biggest problem is the fact that nothing just stands there eating the damage. Stuff moves, and as such, this ability can actually really, really suck.

5) Entropy's DPS sucks and using it either sequentially to keep the DoT up or as a proc before Vamp Bane (it's the best spell it's used ahead of since Burning Light doesn't appear to scale off Might of the Guild, and understandably so, and POTL doesn't scale off anything) is a DPS loss compared to simply weaving more heavy attacks in.

6) Power of the Light: Considering Purifying light has no damage ramifications at all, I didn't use it, but while thematically it may make sense, gameplay wise, Purifying light is worthless. You are better off putting an actual heal on your bars. I digress. The supposition of the 5th DPS loadout was the POTL was a DPS loss. That was not true at all. It is a DPS net gain, single target, but it's cap really kills the ability. Not necessarily the cast time. In fact, the Cast time is what can keep it balanced for PVP. The problem with the ability really has four facets:

It scales like trash. The cap comes quickly and the proc can't seemingly crit exceeding the cap. In fact, Recount didn't show a crit. I was able to hit the cap reliably, but the ability never crit, despite 58% spell crit and quite a few applications.

If only one instance of the ability can exist on the target at any given time, you kill the ability to bring multiple Templars as DPS to any encounter.

The debuff of POTL should apply to all damage DONE ONLY BY THE CASTING TEMPLAR, not just weapon damage.

The damage delay is punitive and stupid. As if it's not bad enough that it takes a year to cast the ability and that clipping kills it entirely, the damage delay simultaneously lowers your DPS at that instant and if the proc doesn't go off your due to a target's death, your dps plummets.

As has been said multiple times:

The ability should be completely reworked. It's a logical place to make a single change and fix Templar ranged DPS and Templar DPS as a whole. However, there's no way to do it without overpowering it in PVP..........And considering that Purifying light has no realistic application, only a very small minority would likely see any problem with you doing a major rework of the spell as it stands.