My apologies for not adding more details.
First of all, let me state that my experiments are inspired by Raddley's work. I strongly suggest his video guide on how to play with a Ray build, which I still find very helpful:
https://www.youtube.com/watch?v=NQVeTZ21Jq8" target="_blank
The video also includes information on haste breakpoints around 4:28, but I'm not sure if that's still accurate. I haven't found any info yet on breakpoints around 40ish ticks. Edit: I assume you mean the number of completed ticks. Depending on your haste the last one might be a partial. There's no need to worry about breakpoints when it comes to the total DPS.
That being said, I see two applications for this build.
One is to provide ST burst damage in M+ to nuke priority adds. You can proc Sephuz with your pet's nova reliably and consistently on cooldown and you'll be able to line up every second Sephuz proc with a ray channel and a rune. If you have at least one IV relic you'll also be able to line up every second Ray channel with both a Sephuz proc as well as the IV damage buff. What I do on trash is to drop a Rune, then use my burst macro of IV+Ray while I cast my pet's nova on the target at the same time. After the channel I immediately drop the second rune. Since I triggered Sephuz with a nova, depending on the group size I'll have between 1 and 3 procs, which I then dump before following it up with an ebonbolt into a double ice lance. After that, all priority adds are dead and I move on to AOE. I continue with frozen orb into the aoe rotation and proc Sephuz as soon as it's ready, again with the nova. Whether or not I can extend IV into the next ray is up to RNG, but since every instance has different timings I don't worry too much about it actually. The DPS during trash is primarily done by aligning the ray with the procs, not by keeping up IV at all cost. I'm happy if I can reach the second ray after I've successfully covered both my ST an AOE cooldowns with it.
The second is to provide high ST damage during comparatively short boss fights. This mainly applies to M+ bosses. The build might work for serious raid fights, but the rotation is extremely punishing and playing with the ray is a no-go on bosses with high movement. To be honest, I'm still working on it. It's also not advisable if you can't proc Sephuz reliably. However, on any boss on farm status that dies within three minutes you can have great fun with it. I completely destroy our other DPS if WitD procs when I start channelling.
Regarding legendaries, I basically run two sets. On trash I'm playing with Sephuz and Zann'esu, which both synergize very well. On bosses I'm playing with Shard and Norgannon's. The boots are almost mandatory for this build, not because of their stats but because the Norgannon's proc allows you to keep channelling the ray if you have to move. That eliminates the main downside of the build, which is the lack of mobility during the burst phase.
What I'm still struggling with is to find the optimal rotation. Raddley suggested a fairly optimized rotation, but that was before the introduction of WitD as well as without the inclusion of Sephuz into the rotation. The problem is that ideally you'd want to throw out all of your ice lance generators early, but if the trinket procs at any time within the first 20 seconds you immediately have to drop a rune and start channelling. You essentially face a tradeoff between delaying cooldowns and munching procs.
I'd greatly appreciate any suggestions.
Thanks,
Katsu.