There are eleven five star bombs in the game. Only three of them really have much of a point, though: ash of agni, shivermist buster, and voltaic tempest. In nearly any circumstance that you can think of, one of those three bombs will be the best five star bomb for the situation.

Many players don't carry any bombs at all, so it's hardly the case that bombs are wildly overpowered. Thus, the solution is to strengthen the other mobs, not to nerf the few that people use.

If you need crowd control, shivermist buster is by far the best, except against mobs that are immune to freeze. Venom veiler makes it so that mobs don't hurt as badly if they hit you. Stagger storm makes it so that mobs don't move as quickly. Shivermist buster completely locks them in place, which is far more effective.

If you need damage, then ash of agni wins easily. A lot of bombs do direct damage. Ash of agni makes it so that even if you miss a mob entirely and it wanders into range well after the bomb exploded, it still deals the damage even then. And it does about as much damage as a pure damage bomb. That makes a bomb that does damage only pretty much pointless.

Another problem with direct damage bombs is that they just don't do enough damage. You run around charging the bomb, unable to block that whole time, and then when you finally detonate the bomb, you only do about as much damage as if you had hit the mobs with a sword. Once. Now, being able to hit several mobs at once is nice. But you could also have done that with a sword, and blocked as needed. Or charged a sword, and sometimes the charged sword attack will do as much damage when you unleash it as a direct damage bomb that hits six or eight mobs. And it will focus the damage better, so that you kill something and thin the mobs, rather than just doing a little bit of damage to everything.

I would propose taking the non-condition bombs and greatly increasing their damage output. That means nitronome, big angry bomb, irontech destroyer, graviton vortex, electron vortex, and dark briar barrage. Somewhere around double the current damage should do it. Leave the blast bomb lines' knockback, the vortex lines' suction, and spine cone bomb line's knockdown the same as they are now, but just change the damage.

Meanwhile, among the condition bombs, the issue is that fire, freeze, and shock are much nastier conditions than stun or poison. To compensate for this, I'd propose having the venom veiler and stagger storm lines apply moderate or even strong conditions, rather than minor. Stunning a mob isn't as useful as freezing or shocking it, but if you stun it for a lot longer than you freeze or shock it, it would be more balanced.

Finally, there are some fans of the crystal bomb lines, but those only go up to four stars. Those can do massive damage to a single mob if you line it up right, so a five star version of them might be balanced right away. But there should be a five star version of them, so please create one.