Like the other tier 6 talents, Elemental Blast should have a support mechanic.
The two most practical options would include:
-Elemental blast heals the caster for a balanced % of the damage dealt.
-Elemental blast damages an enemy target for x amount or heals a friendly target for a balanced amount.
The fact is Elemental blast is the only tier 6 heal class talent other then Monks white tiger that doesn't directly include a healing mechanic. 2 out of 15 talents that should heal or buff heals directly.
Act; Shaman talent tree is a mess mainly because they are trying to balance a healer, a caster, and a melee. Sadly, we don't get to have fun DPS choices as a result.
EB is a tough one to balance and make useful for Resto. I use it pretty much on any fight that I heal that isn't grueling. Ideally, I'd Love for it to have some form of Atonement, but tbh that'd be OP for Ele and Enhance.
The least they could do is have it give back 6k or more mana, so that way its not a choice whether I want to cast LB or EB as Resto.
Zeleros; Well, Elemental Blast changes for Enhancement shamans to provide for agility. And many other abilities in different trees change depending on your spec. Why cant elemental blast do that?
The spell could change to do healing instead of damage for a resto shaman only. Or even provide spirit to make it more appealing for restos.
Shaylana; This spell just feels awkward in the rotation for me. I can't figure it out. When it procs haste, I feel stupid when I use Fulmination and Instant Lava Bursts. (I want to refresh Flame Shock and cast more cast time spells!) When it procs crit, I feel stupid when I use Lava Burst. (I want to Fulmination and cast Lightning Bolts!) When it procs Mastery, I feel stupid when I am at the point where I'm managing Shocks. (I want to cast LBs of any kind!)
It just seems clunky enough for me that I just decided to go with Primal Elementalist. I hate the Warlock Demo rotation more, but it just seems more manageable than Ele Blast rotations. I dunno if Ret is still like a jackpot wheel of suddenly glowing actions buttons. If it is, that's why I left that spec behind. Just too random.
So I get it - I get why you're asking that it should be a support spell of some sort. I would even like it a lot more if the buff would last longer than the cool down. That way, if you need to delay casting it for Lava Burst procs or Shock Juggling, it doesn't feel punishing. It's just not designed that way.