I like a ton of what you have here. Particularly the following:
Aftershock
Changing this to a simpler effect where mini-elementals are spawned to do fairly basic AoE or ST attacks is a great idea to contrast with Surge of Power
Master of the Elements
Having it stack X times would be good. However, I think if you did this you might want to switch it to stacking off of Lightning Bolt and Chain Lightning and then have it usable on everything but the Lightning Spells.
Otherwise, definitely buff the effect, this should be a core thing to Elemental shaman in many most builds
Rolling Magma
Absolutely make Lightning Bolt and Chain Lightning interact with the CDR of Primordial Wave
–Some other ideas–
Mandatory, Give Us Raid Buff Please, We would like our raids to enjoy our presence
Ascendance and DRE
Rework Ascendance so that it doesn’t just give free access to Lava Burst. Spell weaving should still be present in Ascendance, maybe it change everything to have a fire effect and damage is increased by your Crit%, also make it reduce the recharge of Lava Burst, not eliminate the recharge entirely (some synergy with Master of the Elements here)
Primordial Surge
Delete this or rework this, we need to trim down the Lava Burst accessibility.
Lava Burst
Make this scale with Crit% somehow… Maybe make it so there is an additional Overload that rolls on Crit% instead of Mastery%. Just increasing damage based on Crit% works too, just steps on Ascendance’s toes a bit.
Icefury
This is a very controversial ability. Maybe make this more like Glacial Spike. Make Frost Shock have a 6 second CD and generate Maelstrom, make it do way more damage, each Frost Shock builds up a buff (animated as little frosty orbs floating around your character). After 4 or 5, Frost Shock changes to Icefury, where you send these orbs flying at the target to do big damage and generate a burst of maelstrom. Electrified Shocks would do what it does now, causes Frost Shock to cleave and apply the Nature Dmg Amp.
Flux Melting
Replace this. Using the new Icefury above, you could make this reduce the number of Frost Shock (orbs) stacks you need to Icefury. Making this the Single Target version where you get more consistent Maelstrom gains and big damage instances from Icefury
Searing Flames
This is essentially Magma Chamber, just giving you more Spenders instead of stronger hitting Spenders. Maybe move Skybreaker’s Fiery Demise here as a 2pt node
Choice Node of Windspeaker’s Lava Resurgence
If you move Skybreaker’s to replace Searing Flames, maybe put something similar to the Lava Burst Cleave (S3 4pc) here. Where Spenders causes Earthen Spikes to fire at all of your Flame Shocked enemies.
Echoes of the Great Sundering
Make this similar to Ferocious Bite on Feral Druid, where Earthquake can spend additional Maelstrom to do more damage. The 2 pts then increase the amount of damage that is added for the Maelstrom spent
Primal Elementalist
Bring this baseline, just make our Elementals do more damage and be more impactful generally. Also change the CD of Elementals to 2 minutes
Call of Fire and Call of Thunder
These talents buffing Flame Shock, Lava Burst, and other Fire Spells or Lightning Spells is bad, we don’t want to split the tree up into Lightning vs. Fire. Maybe make these more neutral but still themed where Call of Thunder (or maybe rename to Call of Air) gives Haste% and Call of Fire gives Crit% (which would work well if Lava Burst scaled off Crit). Better yet, remove these entirely and replace with something more interesting.
The Second Stormkeeper Charge
This has never been taken because it only gives 1 more Stormkeeper use in a fight. Change this to something else. You could make this similar to old Lightning Rod where you would mark a target (but with a Spender) and then it would pulse lightning AoE damage based on the Lightning Damage you do. This could be Limit of 1 and tuned accordingly so that it is the simpler alternative to DFs Lightning Rod