Basically: look at what the weapon does, then ask if the affix makes it worse.
If the weapon generates gems, then anything that destroys, explodes, or otherwise messes up that generation will cost you free turns so you don’t want it.
Same with a storm. Every storm reads, “Give your opponent 8 free turns.” You don’t want them.
@locoblutaxt That’s pretty much it! Along with the Hex upgrade on Essence of Evil, as mentioned by @oninowon, which can have unwanted effects.
Like @Slypenslyde mentioned, a lot of it is contextual.
‘Create a Gem’ is usually the worst offender.
I can’t think of any ‘Explode a Gem’ upgrades that still exist, aside from Death Knell’s ‘Destroy a Doomskull’, but the free turn makes that useful
‘Destroy X Gems/Skulls’ would be next, since although it can ruin Gem creations (e.g. Darkshot) or set up a favorable board for the AI, it at least gives you some mana and I think has an increased chance of turning out okay
This would then be followed by ‘Create a Storm’ upgrades, imo, in terms of offensiveness/‘damage’/significant and irreversible changes to the function of a weapon. Storms are great! They can often benefit you. As you mentioned, though, you might not always want them in a specific team, so a weapon with that upgrade becomes worse in that context; its versatility has been reduced. Mountain Crusher is generally always improved by the Duststorm is makes, and Jar of Eyes with its Icestorm is very strong – I tend to be very cautious with upgrades, and I’ve upgraded both of these. I can imagine situations where I might not want the storms, though, and there are other weapons that are much worse, more dangerous, or change its use more dramatically.
The Hex upgrade for Essence of Evil has been particularly noted to be a problem or risk for Delves, I believe, where a previously cc’d enemy can be transformed into a healthy troop with high stats that can one-shot you unexpectedly or mess with your troop order. This may apply too other modes, too, but perhaps with less dire consequences; the fact remains that it can backfire, however.
Imo, this is a pretty good list for Devs to review that covers the range of complaints (and I’ll always be happy to go through the list and comment on specific weapons and their upgrades).
Just a minor addition, board manipulation is only considered bad if it runs counter to what the weapon spell does. A spell that already creates, say, green gems doesn’t get worse if the upgrade adds more green gems. Doomed Blade and Doomed Club would actually be great if their upgrade created a Doomskull instead of a blue/brown gem.
I agree that the gem generation ‘boost’ is the main offender but the others that are mentioned here can easily compromise a strong position in the game. I absolutely fail to understand why an affix costing resources to attain should potentially be damaging to the extent that it can in fact cause defeat as an almost immediate consequence. And these design blips are hardly rare in occurrence: they just keep coming. Class trees interacting with traits and weapons can also be problematic. I feel that this impairs the opportunity for players to be more creative because they avoid certain things because they know the pitfalls that accompany the troop, weapon etc. Creating a gem which scuppers the quad you were about to make is infuriating.