@Pseudothol Here are my thoughts on your ideas! I don't mean to sound rude in these but simply serve as feedback.

Blade of the Regent:

"Maelstrom Weapon can now be consumed from Arcane Blast."
I have trouble understanding the phrasing of this part. Does it mean you want Arcane Blast to remove 1 stack of Maelstrom Weapon as if Maelstrom was the Arcane Blast buff? What if it was made so you have a chance to gain Arcane Blast buff whenever you hit with a melee attack or gain a Maelstrom Weapon buff?

The "unleash a flurry of attacks" effect; would this be at the speed of casting arcane missiles, and would this be channelled, keeping you stationary during this, almost like Bladestorm?

Arcane Missiles, Missile Barrage and Cleave are part of these, to make those effects separate requirements inside the LRE, so you can benefit from them if you also have those abilities learned.

Cleave that burns mana from the target? Cleave costs 20 rage (unmodified by other talents), so it would always burn 100 mana from a target if it's 5mana per rage spent. 100 mana isn't much at a first glance, but then you realize Cleave has no cooldown beside your attack speed. The LRE forces you to use a polearm, which is usually medium attack speed compared to other weapons, unless you have attack speed increases. So 100 mana burn every 2sec-ish, assuming you have rage to sustain. Then it also increases the damage of the Cleave? There's a reason why Drain Mana and Mana Burn spells are so expensive to use, so I feel there should some negative added to Cleave to balance it out. Otherwise it gets a little too strong.

I don't understand Blood Glaive's Arcane and Physical damage split deal. Do you mean it splits your physical damage dealt in half and deals it as arcane instead? Or takes the amount of physical damage you would deal and adds that same amount as added arcane? Or is it like a super strong Manaforged Weapon (Rare RE), where it just adds some arcane damage? And how would this effect combine with the "flurry of attacks" when casting missles? That part needs to be specified better. Also, 30% dmg increase is kinda huge, since due to the arcane/physical split, you also just deal 30% extra dmg with the arcane part.

Arcane Empowerment is too powerful due to several factors. You already generate mana from melee attacking and getting hit, so wanting more rage from your spells is strong. Having Cleave hits give you stack of Maelstrom is strong too, as it's supposed to be a chance on hit to gain that. Added arcane spell damage on top of all that is broken. This part could be its own entire Epic RE.

Reactive Adaption:

These are buffs I presume. How long would they last and would they stack?

Sun Bear:

I feel if you're going to get 35% crit chance for Maul when you Growl, there should be a cooldown for when it can apply. Otherwise you might as well just make it so your Maul always has increased crit chance. But that'd be broken too.

Sun Bear's effects? Holy molly, 100 flat AP and Str gives extra AP and 300% increased auto attack and Maul dmg? Plus 100% dmg more from Solar Aggression, that also now deals part of that dmg as AoE? Gain extra EXTRA dmg through strength buff from Overheat? 10% added fire damage? And Maul then crits? This is going to hit harder than Execution. Hella broken.
But I really do love the idea of a DPS focused bear, but it's hard to balance it so it can compete with cat form (although cat form is also overpowered in some ways).

It's a Trap!

Why transform Holy Wrath instead making it its own ability altogether?
I like the idea of frost damage traps, so it isn't just fire traps that can do it, and nicely balanced by removing the slow/freezing, so there is a cost to it.

"Damaging an enemy with traps increases the damage and critical strike chance of Trapper's Wrath" - Is that why you want Holy Wrath as a transformed ability? You want the Holy Wrath to still be the AoE holy dmg spell, but with the added effect of Trapper's Wrath? In that case there shouldn't be a need to transform Holy Wrath, but simply make it a requirement and rephrase it so the Trapper's Wrath effects apply when enemies are hit by Holy Wrath.

Other than that, good RE.

Echoing Blast:

50% less mana cost is steep. The way the shock spells are balanced for being instant high-dmg spells is through their high mana cost. Even a 25% mana cost reduction would be a lot. Then you also write you want to increase the damage, debuff duration and effects, which already makes it crawl into overpowered range.
On top of that, here is a free cast of a Shock after just casting one thanks to the reverberation effect. Even if it has a cooldown, it's still really strong.

I'm a fan of all the added shock effects though. Honestly, just having a LRE with those shock changes could work.

I'm curious about these durations though, just to poke at your brain... Why 4.5 seconds for the damage reduction? Why 36s cooldown? Why 18s duration increase on Earth Shock and 18s duration on Frost Shock's cast speed reduction? I feel like you have some calculation going on behind these that I can't see through.

Eruption:

I'm a fan of making a Hunter/Shaman melee synergy. Pretty rare combo.
How much bonus scaling from AP are we talking with these though? 10%? 25%?

Dormancy effect seems interesting. How long does the buff last though? It's important to know, so there is a clear idea of how easy/hard it is to build up to 10 stacks for the big boom.
On that note, 100% scaling from AP AND deals its dmg as AoE seems a bit too strong, when you already have Lava Burst scale with AP in the first part of the RE, on top of guaranteed crit on AoE'd Flame Shocked enemies.
Perhaps it could be balanced in the way that each stack of Dormancy increases Lava Burst's mana cost per stack?