i like assault frigs and i hate t3d's, dont think they thought about assault frigs when they released t3d's, my answer to nerfing t3d's is either remove them or buff assault frigs so they can compete

There need to be more way that the enemy can exploit a T3Ds weakness in particular modes.

Without the modes they're just destroyers with relatively simple stats. But with them they surpass other ships at the role. Speed mode makes T3Ds faster than the majority of frigs. Defense mode makes them on par with cruisers. You can get some other frigs with similar tank but it takes a lot more bling with less turnover (22k EHP wolves exist, but not worth it when 22k +300HP/s svipuls do too for a cheaper price tag and the magical insurance they get).

For starters, the insurance needs to either go, or other ships need a similar trait. It's just too cheap to fly T3Ds. That's not to say that the insurance has no merit - it encourages you to welp yourself against unfavourable odds for the promised cost of a T2 frig but with the strength of a cruiser with frigate sized sigs and such. But that's not something that should be attached to T3Ds.

Base stats could be weaker. So that in a mode it's biased heavily to a particular role whilst being worse than average of the same size at other roles. And forcing a pilot to switch modes becomes a fighting strategy.

Hecate is the most balanced but shouldn't be the template for the rest. Having sentinels be the primary counter to this class is no better than it is now.

One of the problems with the Proteus and it's stupid levels of tank is the ability to fit 2 1600 plates. That's way too much PG to work with and still have room for a full rack of guns. And it still even has the ability to pick up the ewar bonus subsystem. 3 rigs doesn't exactly help the problem either. HACs can only fit 2, and medium tech 2 trimarks aren't even that expensive anymore.

edit: I should have a better attitude towards people.

Just check out 10mn fits and ultrathrasher fits, those are the real culprits. When you can comfortably go solo against cruiser gangs, something is off.