A few suggestions I have from my own testing. Grenade Fan - When spammed like a maniac, combined with her implosion from her 4 and a decent duration and strength build I was able to wipe 9 corrupted heavy gunners at level 130 most of the time. However this was only after dropping my 4 so I could spam endlessly my 1 to make it worthwhile. Most people seem to be suggesting limiting the number of her 1 and 2 but upping the damage by a lot. I understand the issue DE faces with Protea though. Her 4 by design allows you to just spam your abilities, what's the point of it if you limit the number of grenades, or turrets she can throw out? That being said the damage when not spamming her 1 endlessly is abysmal. They like Vauban's flechettes need to scale with enemies, as does her 2. But there in lies the problem. How do you make her abilities do good damage without spamming them, without them being broken when you use them with her 4 and spam them to no end. I've a few ideas:
Grenades MUST scale with enemies. I'm not trying to hate on DE I'm really not, but I honestly do not understand why they keep giving us damaging abilities that don't scale when it's been shown time and again they become useless. I'm not trying to call them out, I really am just confused as to their reasoning. I'm sure they must have one.
You can only have so many grenades on the field at a time, however, throwing grenades into existing grenades either refreshes, or adds to their timer and increases their damage. Think a combo between Vauban's vortex and Gara's 4 and 2 synergy. This would allow you to either cover a wide area in grenades that deal ok damage, or focus one area and deal incredible damage. If this is too powerful then perhaps this function is only available during her 4 and when she rewinds, she rewinds the grenades with her, making it only possible in that window, allowing her to spam and have them gain near infinite scaling but with restrictions.
Add a small vortex effect to the grenades to allow them to keep enemies within for more damage. This could go two ways. Either they have a powerful pull but only within a small radius or only for X amount of enemies. Or they have a weak pull, something an enemy that is running can get out of, but if they stand still it will gradually pull them back in and make them effectively slower within the field so they can't escape so quickly.
Blaze Artillery - I was so excited for this one because it seems so cool. The turret has only a max number of shots it can fire AND a timer. This to me is a bad call since you either get a huge group of enemies and the turret fires all it's shots and is gone before it can dig into the meat of them, or you have a sparse number of enemies but the turret deals with those and then wastes all it's extra shots since it's on such a short timer. I also outlined a lot of issues above with the idea of this and her 1 needing to be spammable and not OP but also usable without spamming. I know they don't want us to have a regular turret in the game, I understand their reasons for this, but I do think those reasons are not really as big a deal as they think. However with this in mind here are my suggestions:
Surprising nobody, this needs scaling damage too. The concept of it getting more powerful with each shot is good but not enough to help it, especially with the ammo situation, if it had unlimited ammo and a longer duration then this could end up working...eventually. It would still need to really ramp up by a lot to be able to deal good damage to high level enemies so I think a better option would be to have the damage scale with their level.
Ever play The Division 2? There's a turret in that called the sniper turret and it has a very interesting method of use. It does not fire on it's own at all and instead must be manually fired by hitting the associated button again while it is locked onto an enemy. It will lock onto the enemy closest to your reticle. This could work really well with Protea. Make the turret have no duration, no timer, and give it much much higher and scaling damage, but make her manually fire it, and every time she does it consumes energy as it's "ammo". This would eliminate the fear of "the game playing itself" but would allow it to still be powerful and also allow her to spam it with her 4. Again like my idea with her 1, this could get out of hand, spamming it to build up it's damage with her 4 active, then after that continuing to use it without it active but the damage still ramped up. Like before this could be fixed by having her turret deactivate when she rewinds. Also to remove the turret manually it could be that you just hold the button.
Lastly you could have it have infinite ammo, infinite duration, but like Grendel's 4 have it gradually use more and more and more energy. If you do this I think it would also be nice to be able to have some means to direct your turrets to focus fire on one particular enemy.
Dispensary - A lot of people are complaining that the dispensary takes too long to produce it's products, but personally I'm ok with it as is. If you were able to spam them in your 4 then you'd have this perpetual motion machine of infinite ammo/energy/health and that would definitely be OP. At the rate they produce now I think it's pretty fine as is. That being said I do have Arcane energize on at max rank which helps a lot so perhaps these could work:
Additional activation's of her 3 cause it to instantly produce a random item, allowing you to roll the dice to get more energy/ammo/health but none of it is guaranteed.
Allowing you to cycle through the various items the dispenser can drop allowing you to just focus on energy if you so desire but of course it is still produced more slowly.
Dispensary has an AOE around it that if you kill them within it they have a chance to "charge" the dispenser and cause it to drop another random item.
Temporal Anchor - Honestly for the most part like the last one I quite like this power as is. However in it's current state it's really only useful for spamming abilities. These may help:
Allow her buffs similar to Gauss' 4 while it is active.
Allow her to apply Cold procs to enemies while active (Get it?...slowing them down?...cuz like...time and stuff?...)
Any kind of special buffs to her abilities and even weapons while active
In conclusion I like Protea in concept and design. I even like her play-style though it really just does not work currently at any higher level play. Hopefully I was able to provide any ideas that may assist in improving her in some way. If not, then I apologize for wasting your time and I hope somebody else was able to give ideas that could assist. Thank you for reading and have a great day.
PS. Her passive is good no worries there, but her signature gun is V boring. Any chance we could get an Alt fire or just something to make it more unique than "another machine pistol?" if not it's not the end of the world but giving it the bonus of better ammo economy with Protea is kinda dumb since she can already produce her own ammo anyway so it doesn't really need that. Ok bye.