The closest troop should be Zephyros: Destroy a Column. Deal [Magic + 8] damage randomly split among enemies, boosted by Yellow Gems destroyed. [10x]
Deals [Magic + 8] damage randomly split amongst enemies, boosted by Yellow Gems. Summon a Lightstorm. [3x]
Of course, Zephyros is a meh troop. Strygeek has the advantage to help with his Lightstorm which could be interesting in a full yellow troop.
Split damage is difficult to balance because when only one troop is remaining it becomes a target spell and so, it should be at the same range than this kind of spell. Here, we have a 12+8+14+3x10=64 damage or 16 damage to all, not too bad. I will certainly increase the multiplier to x4.
Else, the issue is maybe the split damage mechanic: maybe a damage bonus should be added according to the number of remaining troops…
Another issue with this troop: imagine you cast him once so you have your Lightstorm and then you use an exploder. Then, the board is full of yellow gems like 20 of them. A great damage bonus but of course there will be 4+match that you will have to take… So maybe a “If there are 13 or more Yellow gems, gain an extra turn.” could be nice, so you can cast him even if there is many yellow gems.