So I am assuming when you explode a gem that gems can’t “double dip.” If I explode a gem and it destroys the gem to the right of it, if a gem to the right of that one also explodes, it can’t collect the same mana from the gem to the left of that one. That means each gem can be destroyed only once, for 50% of the mana. So for instance, on this board:

If I were able to explode all the gems on the board, I would deal 11 skull damage (6+5) and I would collect (of the colors I can) half of each color mana, rounded up?, for a total of: 5 yellow, 6 brown, 6 green, 4 blue, and 4 purple, plus any matches on the way down.

Let’s find out, Gorgotha is going to explode 32 gems! Alright… here’s the board RIGHT after the board exploded:

Enemy took 12 damage – possibly 5 from Doomskull and then 1 extra from the Doomskull exploding. And I collected: 4 purple, a minimum of 10 green/blue, and at least 11 yellow/brown. So I got exactly what I was expecting.

And there in lies my question. Exploding 32 gems is clearly overkill. For SOME troops and weapons, it’s necessarily because of restrictions, but even then there is a cutoff. For instance, Essence of Evil or Mountaincrusher explodes specific colors, but you’re very rarely going to need to explode more than 15 of them.

But if you want to explode the whole board, what’s the minimum you need? Well, you need 4 explosions for each corner, then 4 more for the 2 rows and columns in between them, then 1 for the 4 gems in the center. That’s 9 perfectly placed explosions. But that brings up another question: can two gems explode on top of each other? For instance, could a gem explode, and then another gem explode one of the gems the first one was destroying? If so, that means you’d miss out on 3 gems being destroyed.

But as far as the maximum amount of mana, well, that’s 32, assuming there are no skulls on the board, since 64 gems will explode and you’ll get half the mana, and if it’s always picking a new location to explode gems, then I think the minimum # of explosions you’d ever need would be 11, which means a troop like Infernus which explodes 5 random gems destroys nearly half the board, bringing in ~12 mana. Compare that to Obsidius which flat out destroys a 5x5 block for 25 mana.

In other words… the new set of troops that destroy 5x5 is superior unless you can explode ~9-10+ gems, and random is probably always better, given that there might be insufficient numbers of specific colors of gems to explode that many.