Category Five is not just about what it does in the absence of your other powers - it has synergy with your other storm blast powers when they are used within its AoE; It's like complaining about mastermind pets underperforming, but neglecting to take any of the upgrades...
Honestly, I saw it more as the original villain ATs, (as they functioned when CoV launched), skewing their focus more toward damage and solo play, vs the hero ATs, with stalkers being more specialized scrappers, and brutes being berserker tanks.
Welcome back! If you're finding that you're lagging, try changing the option to always show player names to only showing them when selected or on mouse-over - the GUI can impose a hefty penalty on performance. Also slightly reduce your draw distance under the graphics options, and lower particles. Cheers!
Defenders get the greatest benefit out of tactics, which is tohit instead of just an acc buff, AND it benefits your entire team. It can be a costly toggle to run, but provides a huge benefit.
O2 isn't in storm blast, and very few blast sets actually have a self heal. I don't find the damage to be bad - you just need to fully exploit the extra lightning strikes that storm cell and category 5 utilize; It'd be like playing beam rifle and not utilizing disintegrate...
That's why I make liberal use of the "goto passive" bind I listed earlier - make all your pets ignore everything and go where you clicked - send them away if they have aggro you can't manage. If nothing else, it could buy you and your team some time...
"Energy" is a very generic term. CoH treats it separately from psychic energy, dark/negative energy, and so on. Heck, fire is basically energy, as is blunt force, (I differentiate it from lethal damage, as that is more about cleaving/separating something's intact form). Even cold damage could be construed as forcibly removing energy from a target, thereby causing damage.
Stalkers get a very large bonus to crit chance based upon the number of other teammates. Hide is almost superfluous, except for opening a fight or sneaking past mobs. Heck, there's an ATO that can put you into stealth for a few seconds, without needing the power, (IIRC).
All this arguing about character origin is why I'm glad it is, for all intents and purposes, irrelevant with regard to how your character turns out/performs...
I've been playing my storm/ninjitsu sentinel through end game stuff recently. I use storm cell and category five as often as possible. It's about setting up a kill zone then using your other powers to get the lightning strikes and such to go off. It's very similar to how ice blast has ice storm and blizzard. The difference is that your other powers set off additional sources of damage...
It's really not that hard: Train to 50, unlock the slots, craft stuff to put in them. Yes, you have to convent from threads/shards/empyreans into the actual components each ability requires, but it's really not that difficult to grasp. See more here.
Does being in a TF disable the AFK detection process, or is the player using some other method to bypass that? If so, that seems like more an an issue to be addressed, which would also alleviate the issue in the OP...
It could grant rewards based upon completion of each wave, instead of per enemy. I would also make it so the next wave only begins after defeat of the prior one, instead of some timer, to prevent someone from simply using phase powers or such to avoid the enemies to lengthen their time. Would you need to disable rez powers, or allow players to use everything that their disposal?