Its not the stat gain that allows her to loop forever without looking at the board, that just makes it slightly faster. It is a strong thing to have in combination with the explode and extra turn, sure, but its not the key factor. She would be way over the mark without it.
Primary mana with exploders is not the issue. Cascade mana is. If she doesn’t explode herself to full and doesn’t get a match 4 setup on the new board, the loop self breaks right there. Cascade mana is greater due to spikier cascdes in unity, match 4 surges, and more generous over 5 match calculation. In theory, given “stable” board drops, she casts once to partially charge the team and must use her extra turn to either gather her mana back or go for another troop. In practice, about 90% of the time, something cascades, leading you to another or self fill, for an infinite net gain unless you get really unlucky. I did just Fizziepops and Ragnagord on a team and on one instance I was able to get five casts of ragnagord and eight casts of Fizzbang in the same turn, Ragnagord alone cascading into an extra turn four times and Fizzbang cascading herself to full at least four times. Unfortunately, exploders have been kinda broken for so long that this will feel like the baseline and complain that exploders got nerfed because a troop was broken in other aspects, but honestly, she has just highlighted something that has been a problem for a while by making mostly favorable RNG always favorable.
For now, I propose give an extra turn if there were 13 or more green on the board before exploding. Stat gain no longer scales based on magic and is a small, fixed amount. Still allow her to work with setup, but you need setup and at least a modicum of focus to let it continue. As drafted, she is not even too reliant on green because you so can easily cascade green back on the board, and if it is on the bottom 2/3, cascade something else away, and continue casting.
Alternatively, another way to nerf her into the ground on defense would be to replace Stealthy with something else. Yeah, it fits, but gameplay first, then flavor. Without stealthy she is food to the thing put in the game specifically as an attempt to counter her race, and then the entire team is toast. I don’t know what the obsession is with marking strong support troops have stealthy and taking away most the counterplay you might have, but I wish it would stop.
Wisp should have been empowered and never had the charm. Different colored war sphinx argument aside, its role should have been to turn your bad starting board into a potentially good one and nothing else, not deal 60+ damage on one mana match with extra turn that allows him to refill himself to the point where two of them can kill a troop on the first turn taken and soften the rest of the team to a degree that they can be killed with the next spell cast while also filling that troop. Yes, this a a very limited role, but also a very useful one in some situations. The worst part about this troop is that it is only really deadly sometimes, it has to charm the right troops, line up the right mana to fill itself or another thing. So given a board that does not favor you and allow turn 1 counter play, a chance at you getting run over, and a chance at it being trivial without you being able to interact with how the battle is playing out in any meaningful way. And a link on a 9 mana troop that already starts with mana seems a bit unnecessary. And stealthy, so again, you can’t even target it. He can keep dispel and the 9 mana cost if he is going to keep the link, swift > empowered, remove charm, stealthy with magic heart or something useless. Alternatively, add charm immune to the game and give a few of the weaker charm troops the ability to target instead of random. Or a contrived counter that reduces the attack of everyone on your team to 0 with empowered (leshy is too slow and is immune to entangle himself if you traited him).