I understand that the item is going to be nerfed in the upcoming patch, and while I am sad to see the spell damage go from 150 to 92, in the grand scheme of things I don't mind that as much as the second nerf which implements a 30 second duration to stacks rather than having them be permanent.

In terms of game mechanics/gameplay alone, I simply do not think it is necessary. Stacks are already (relatively) difficult to accrue, and you are more likely to be dead before you reach full stacks anyway. In Cyrodiil you have to go out of your way to find NPCs to kill in order to get stacks, and it isn't until you start to look that you realise there actually are not that many ambient NPCs around for you to kill. In battlegrounds there are literally none, which means you have to get stacks by killing players since you cannot bring your stacks with you through loading screens. And in PvE there is also virtually nothing to kill unless a boss in question has a lot of adds, or unless you managed to get the killing blow on every single trash mob before the boss AND managed to not die. The difficulty of using this item will be amplified to untold levels if stacks expire in 30 seconds.

The stacks were always (relatively) difficult to gain, but the reward was worth it, as it allowed you to become a glass cannon (one of my favourite styles of gameplay). The downside of course was that you cannot enter sneak without clearing your stacks, and it only takes a few hits from any given player (or mob) to kill you, and given that your healing/shields are massively nerfed with full stacks, there is little hope of surviving a 1v1 encounter like that. In short, the downsides are already present.

To me those downsides are all the Thrassian Stranglers need, instituting a 30 second timer on stacks means that (as I elaborated above) it will be virtually impossible to ever gain many stacks, and even more impossible to arrive at full stacks, and the item will stop being worthwhile to use (dare I say "worthless"). I've heard that stamina players say there is no effective counter to the Stranglers, but I maintain that the "counter" is already built into the item. The user is incredibly fragile and can be killed easily, even if they are in a group. It just requires that you target the user to kill them with relative ease. The "counter" is to kill them, not to use your abilities to block its damage. The POINT of the item is to boost damage, if people could just counter it through negating its function, it would be a worthless item to use. It would be like (excuse my medieval weapon analogy) someone "nerfing" plate armour by making it out of flimsy aluminium rather than having assailants change out their swords for warhammers to pummel the person in the plate. The POINT of plate armour is to be hardy and resistant (especially to swords), but you are still vulnerable to blunt weapons like warhammers, so assailants should adapt to this different opponent rather than having the point of the opponent's armament be made null.

If you are keen on giving the Stranglers a bigger nerf than just reducing its Spell Damage, consider modifying its effect to keep the core function, but provide additional weaknesses. Such as increasing the cost of abilities by 0.5% (or 1%) per stack, meaning a 10% (or 20%) ability cost increase at full stacks. This would also contribute to the fantasy of the item, as you give up more in exchange for power, and must channel greater magicka (or stamina) reserves to maintain that level of power—the more powerful you are/want to be, the more magicka (or stamina) you must use. This would also force the users of the Stranglers to consider increasing their max magicka/stamina rather than just stacking Spell/Weapon Damage buffs. It would make them try to find an optimal balance between the two.

Now on to my personal plea. I am a massive fan of glass cannon builds; I've always loved the fantasy of them, and was ecstatic to see the Thrassian Stranglers added into the game, as they effectively change your entire playstyle when using them. While the Spell Damage nerf is a big blow to the item, what would really kill it is the 30 second stack duration, as it almost entirely removes the glass cannon aspect from any build you use. No longer will you actually have full stacks for any meaningful amount of time, and any small breaks you take will erase your progress. Thus, making a pure glass cannon build is no longer practical, as you'll rarely be in a position to use the build to its fullest potential. It would be much more practical to add the Stranglers to another build as an add-on item, and then just forget about it. That is not the gameplay I am interested in seeing, and I truly hope you will reconsider the 30 second duration to stacks. It is not necessary to remove what makes this item so appealing and special to create balance, like my earlier ability cost suggestion, there are a myriad of other effects you can implement while maintaining the items functionality and core fantasy.