Alright, here comes my complaints! Fair warning, 95% of my time spent through my first experience in Legendary was filled with FUN. I'm just gonna put down what irritated me most of all compared to the fun. Seriously, I don't regret playing this mod at all. There's a distinct lack of love for Halo 3 mods and this was one of the most fun I've played, much thanks to the care put into giving me so many guns to find (secrets) and use! It scratches an itch I get when I play Mythical Overhaul, where so many guns are fun and have strengths. That being said, I write this from a place of love. I love what you're doing, even with some of the wacky ♥♥♥♥ you're pulling off. One particular favorite of mine that you're doing is that you provide good use of UI to relay when there's a seconary weapon mode to use, to explore the full potential of weapons. I didn't understand the symbols at first though, but it made more sense as I came across others with radiation, electric, etc. Another amazing thing that this one mod manages to do is *make the freaking LMG/Plasma Turret actually viable and fun to use* unlike other iterations I've tried.

Warthog run seems messed up! I'm dying from the mandatory jumps, which forced me to land on weird places to actually win or take alternate routes. I suppose someone missed playtesting the final level. Everything else is just OK, the entire level suffers a bit of weapon variety.

Cortana is least fun of all. I wouldn't say it's down to the roster or combat, it's just *really* uninteresting compared to other levels that has several hidden weapons and tons of variety. It's funny because I tend to play Floodgate and Cortana a lot due to that the sandbox is widely available and shooty on meaty targets. This level needs more love. And for gods sake, how come nobody but one mod (Mythical Overhaul iirc) has figured out how to disable the worst thing about Halo 3, namingly the forced 'cutscenes' with slowdown and eplilepsy-inducing flashes? That damn change should just be mandatory for anyone who wants to play Halo 3 these days.

The Covenant at the penultimate fight with the final brute, wielding the incredible hammer often suffers a 1v1 issue with Arbiter who consistently kept shoving him out of the playable area so I couldn't enjoy the one single instance of that weapon (such a shame it's not anywhere else, believe me I LOOKED.)

Spiker:
There are many wacky changes to the sandbox, but perhaps most bizarre is the Spiker, which I suspect is just errornously designed. Meleeing HURTS the players health pool directly, even if it's the floor.

Mauler:
Oh Mauler, what kind of bruteforced forerunner brain-mutation did you end up with? This gun is actually hilarious, it doesn't do ♥♥♥♥ all other than push enemies (and yourself) off cliffs. It can be used to absolutely insane jumps and speedrunning tricks, which is honestly okay - but is that actually what was intended with this hunk of junk? I'll point to a favorite iteration I like, probably Mythical Overhaul, where the Mauler shoots a gazillion visible spikes and has semi-decent range (unlike the Shotgun, jesus - pinkie demon from Doom had better bite reach than this blunderbuss, it makes the Doom 3 shotgun actually look good) If you don't end up changing this one, I'm okay with it. I'm going to literally jump off The Ark with two of these and pretend I'm lore-accurate Master Chief whose forward momentum is that of a MAC gun.

Flood:
.. having a weird 'death timer' on their corpses exploding was not something I enjoyed, because it was hard to tell when I had dealt enough damage to the corpse to have them destroyed. Bladed weapons could take 3+ hits to shred a single human corpse. I also do *not* enjoy that (and I read this from a comment of yours) you moved the weakspot for the elite flood to their arm.. ? This makes very little sense to me and plays very bad in gameplay, because of the innate bullet magnetism wanting to drag and pull bullets into the head hitbox. It doesn't feel satisfying to do precision weapons thanks to this.

Equipment Invulnerability galore:
There's a *lot* of Invulnerability Charge, which is fine as it only lasts a good five seconds, locks you out of picking up equipment until it runs out and isn't preventing fall damage (to my hellish demise in the warthog run segment..) but one thing I felt myself getting a bit insane from was how many units just pop invulnerability without any real way to tell if they got it (aside from your biggest bosses). I think I could forgive brutes, but flood shooting or meleeing me with it was taking me out of the immersion during fights.

Hmm.. maybe replace their charges with that of a Vitality Booster (which was used a single time in Tsavo Highway if I recall..) and just make them tanky instead. Actually, no.. this would lead to Halo 3 bloom overload due to the overshield look, which easily makes people like me sick (god it's so ridiculously used in some dark maps)

Spike Grenades:
I'm not sure how to feel about them. On one hand, they make Cortana way worse due to activating every single pod in the level with ease, and on the other they are fun with the straight throw. I love sticking enemies with it, even if it has an absurdly long fuse time when it happens. I find the arming over distance awkward. If the spikes instead went in a cone forward, I'd be happier about it.

Needler:
Everything in the game seems to have 'Tough Luck' modifiers on that I tested it with, leading to a handful of kills throughout the entire campaign, but not more. It feels bad, because it's not really an impressive weapon aside of blowing up flood corpses with.

Weapon 'move speeds':
I love the idea, but the execution needs to be refined and doesn't telegraph that well at first to me when I first played. It feels awkward to be so slow with some guns, yet run like Speedy Gonzalez with an SMG or Sword. I found myself strafing/running diagionally a *lot* because the forward momentum felt very bad on some weapons, which feels scuffed. I'd love if you could ensure the movement speed can't be abused like this, as is seen with heavy LMG/plasma turret strafing in vanilla, but just generally raise the movement speed across the board so that walking forward doesn't feel like mudsludging compared to it.

Little tip: You can sort of get around slow movement speed of a dual-wieldable weapon by changing it to the other hand.

I can't think of much more at the time, but I do wanna say that I want a significant ammo boost availability for human weapons that are less common, such as the red-white AR. I note you make use of the 'human ammo equipment' and I think putting more of these would help out a lot with this issue. There's far more 'Covenant ammo equipment' but they do sadly get destroyed most of the time thanks to chain reacting grenades. I haven't laughed so hard at grunts as when I saw one use a Storm Ghost and just absolutely flew off the other side of the map in what must be some kind of Unggoy ridden anxiety to hit the gas when a Spartan appears.

Edit #2 (14th August):

M7A4 PDW / 'Defense' / "white" SMG:
I'm bringing this weapon up as a sort of example of why my experience + previous point on Weapon movement speeds are feeling off.. and can be a bit on the nonsensical side. This weapon allows for a strangely higher *strafing* movement speed than other weapons, such as the Rocket Launcher or Magnum Pistol/back-up magnum - which makes me play diagonally instinctively. What's interesting is that the standard SMG compared to this one lets you run faster, which makes it feel way better (and fits the role/size of the weapon) - and then there's the Silenced SMG / 'M8S' that is slower than both of these in any direction!

Rocket Launcher (our beloved SPNKr):
The rocket launcher suffers from a strange delay for reloading, which I suspect is happening because of the lock-on mechanic. You have to change weapons or wait for the lock-on to disappear in order to reload new rounds, which makes some sections a little more tedious than it should.

SMG:
This is my favorite gun to use, but almost always ends up getting shoehorned into mods as an awkwardly balanced weapon that can't live up to basic cannon fodder extermination. This freaking gun, I just checked, is so bad that it takes *three* entire bullets to kill the infamous Halo 3 rat. That or Crows Nest has some of the tankiest rats spawned on Earth, the skavens of the franchise. The accuracy spread over consistent fire is atrocious. I would LOVE to see some max ammo added for this thing so I don't have to scavenge so much and up the damage or spread to help get value for the time spent screaming bullets on enemies that just laugh at me with Spikers and Plasma

Due to the length of this post I'm going to try and reply to each individual point you brought up:
1: I'll look into the warthog run, and maybe adding a few more weapons into the level via the flood
2: I do agree this level had minimal changes in terms of weapon additions, though I'm always unsure of what weapons to add and where to add them, and for the cortana/gravemind moments many mods actually fully disable them, but I have chosen not to
3: From what I have seen the final chieftain should just teleport back onto the bridge if he falls off, and yes you are correct that weapon does not appear anywhere else
4: This is intentional, partially to balance out it's increased melee damage
5: Intentional, was done for the purposes of MP where it's a movement and displacement tool
6: Vanilla flood combatforms corpses have a delay on them before exploding after taking a certain amount of damage, I may have increased this delay but it is not a new addition entirely, I can look into increasing magnetism on the arm, though the flood form in the head is still a weakpoint with less total HP
7: So your issue was that flood enemies have invincibility? or that they used it when attacking you?
8: Partially changed for close quarters MP maps, also to make it much more unique from the plasma grenade, the explosion when stuck to an object sends shrapnel in a cone
9: The needler is almost untouched from vanilla, I personally playtest on heroic myself so I can't attest to how evasive AI is, unsure if it needs changes
10: Movement acceleration was lowered on purpose, there is no fix to diagonal movement and I do not have any intention of increasing player speed
10A: Very observant of you, I have known about it for a long time but never seen anybody else mention it
11: Ammo economy changes are difficult due to the MP component, and radio pack marines have a chance to drop human ammo when they die, but I can see about adding more of these equipment items to levels
12: I wanted each SMG variant to feel different and distinct, all 4 of them, there are various tradeoffs for the mobility increases or lack thereof
13: As far as I know, no way to change this, blame Bunger
14: Rats in this mod got a health buff, as for the SMG itself it was designed in MP around it's mobility and extreme health damage bonus, hence it's base damage to shields being very poor. if desired I can look at giving it a damage boost against other fleshy targets