A long cast laser doesn’t sound like a “spellslinger” to me. “Spellslinger” is likely a play on “Gunslinger” and everywhere I look it references being “quick on the draw”.
Nothing about “Channel a laser beam for 12 seconds” sounds like being quick - especially if it’s unaffected by haste.
What kind of damage is “Frostwarp” damage? Spellfrost already exists (barely, to be fair) and is a combination of Frost and Arcane schools.
Here are my additional thoughts from an Arcane perspective:
Timelord: Frostwarp Laser can no longer be interrupted, and during the channel you can no longer be stunned, silenced, or be affect by any loss of control effects
12 seconds of total immunity is absurd in PvP and will never work in PvE. “To avoid being stunned, just be a mage.” If you really want your laser beam, this talent is WAY overpowered - especially given how absolutely “meh” the choice it’s fighting with is.
Junction Point: Clearcasting can now have up to 2 additional maximum stacks …
The only purpose of this talent is to make the big laser beam stronger? More maximum stacks of clearcasting really doesn’t help arcane at all right now. In fact, wanting to save your CC procs to cast the laser beam is going to be pretty detrimental to how Nether Precision currently works. Arcane’s non-burst phases are going to be even weaker somehow since we won’t be using CC procs at all - just hoarding them.
Which also means we’ll probably hit the “I’m not getting enough procs” problem we had in Shadowlands. Nether Precision alleviates that pain a lot. But if you’ve got this spell that effectively needs you to have 5 procs of CC before you can use it effectively, it’s going to hurt a LOT when you only managed to get 3 (or they timed out altogether before you were ready)
Frostwarp Battery: Every instance of damage done by Arcane Missiles or Frostwarp Laser generates a stack of Arcane Battery while Arcane Familiar is active.
At 100 stacks, your arcane familiar fires an Arcane detonation at your current target, dealing (300% Spell Power) Arcane damage to the target and all nearby enemies within 8 yards
Why tie this to Arcane Familiar? There’s no reason to force a talent selection just because of flavor. In the frostfire tree, there’s some linking talents between having meteor cast comet storm and comet storm cast meteor, but tying this ability to the familiar “because you can” will make it even harder for Blizzard to fix Rule of Threes and make it a viable talent.
This will effectively do about as much damage as the impact of Meteor (not counting any burn effects after). If you’re saving your CC procs for the 45 second laser beam and doing a full 12 second cast, Frostwarp Laser would need to deal damage 8.34 times per second to be able to cast it as frequently as a meteor (which has a 45 second cooldown). Sure, I see that the intention seems to be that it’ll do full damage to everything it hits, but not only would Blizzard never let that fly, it’d also be unhealthy for the game. M+ would be “pull the whole room and let the mage nuke it” (which, yeah, that’s sorta how it already is, but they usually try to prevent that, not encourage it).
Additionally, the fact that it isn’t controlled by us (procs as soon as it hits 100) means that you could nuke an add that has 1 hp left and lose an absolute ton of damage.
Frostwarp Weaving: Cascading Power now also grants you 1 Clearcasting stack every 4 seconds for 12 seconds when used
Again, why are we tying this to an optional talent? It’s either going to be underutilized because nobody takes the talent or make the talent required in all circumstances. For a talent that’s in the last section, that’s a lot of power to force someone to give up just to make a hero talent work.
Nether Hurricane: Nether Tempest is now permanent and applied to your target whenever your channel your Frostwarp Laser
Why? There’s not really anything exciting about keeping NT around. It’s a pretty weak spell that has incredibly minimal interactions with our kit.
Lifeline: When taking lethal damage, you instead apply a Prismatic Barrier at 200% effectiveness on yourself. If the damage exceeds the combination of your current health and your barrier, you die. 10 minute cooldown
Just put Cauterize in the general tree. Most mages have been asking for Cauterize to be available to all specs anyway, so why give the other two an option for a significantly weaker version of it when we can just have the real thing?
Frostwarp Reverberation
(I’m too lazy to quote the whole thing here)
If we go back to the math I did earlier to see that the laser could deal damage 8.34 times a second, that means this spell will end with a 100% damage increase on it. Which is a lot. If the laser does damage at a more balanced rate (say twice a second), it’ll end at a 24% damage increase - which is half of what Radiant Spark currently does.
Additionally, this is set to replace 2 talents in our tree. Do we need to have those two talents picked for this to work? Or could I avoid the center of the tree and put my points elsewhere to get even more bang for my buck? What about Harmonic Echo? Will that talent affect this new one to effectively let my laser double cleave (since you’ve added another talent for laser cleaving)?
Conclusion
This really doesn’t feel like it’s been thought out for Arcane. It looks like you wanted to add a laser beam and said “let’s put it here!” I’m not confident that any of your suggestions here even mention Arcane Blast, Surge, Barrage, or Explosion - yet somehow Nether Tempest made the cut? That’s not even including things like Presence of Mind, Evocation or Arcane Orb. I feel like these suggestions are trying to reduce arcane to a “spam missiles” build and I’m not for it.
If you really insist on putting a big ol’ laser beam into the mage kit, I honestly think Sunfury would fit the theme better. The Sunfury were Kael’thas’ army in Outland - and he’s known for his desire for power. The Sunfury raided and took Tempest Keep and were responsible for the Manaforges in Netherstorm - so I think they know a thing or two about “power” and “energy” that we could work with. Plus, I think a big firey-arcaney disintegration beam would look cooler than “Ray of Frost but purple”. I don’t know much about how fire plays these days, but a talent that allows Pyroblast to be cast while channeling the laser beam could be interesting (and probably stupidly overpowered - but that’s the direction)