CE was only difficult on Legendary in areas with Elite Officers or higher rank, or any Elite in a Banshee. If you Caution and grenades are helpful in areas with infinite spawning Flood. The Two Betrayals had a lot of annoying enemies. 2 was a grindfest thanks to the absurdly overpowered Jackals that kill you the moment they're alerted to your presence, often shooting the beam sideways out of the barrel to do so. Elites were also ridiculous to go up against in this, pray you don't come up against an ultra piloting a Banshee or you'll need to empty a full Rocket Launcher to kill him. Moonbabies were annoying as hell too, and i ended up using speedrun techniques to cheese a lot of Delta Halo and High Charity, because I was just sick of fighting such uninteresting enemies. Halo 3 was one of the easiest ones, and the Jackal Snipers were significantly toned down in this, despite being a one shot kill. Brutes were relatively easy to dispose of and so were the flood, with the only genuinely hard parts of the game being the 2 infamous rooms on the level Cortana. Thankfully buggy AI prevented the Reactor Room from being a hailstorm of fire from those bullshit pure forms. It's weird that difficulty settings didn't seem to affect the Flood levels, aside from Elite combat forms having shields. ODST was just bullshit and gave every player a good reason to hate engineers. Your only option was the noob combo, especially with the Automag taking almost all of its ammo just to deplete any Brute's shields. It provided some difficulty in areas with a lot of enemies, but it wasn't the hardest game overall. Halo 4 was only ever hard when you were fighting Covenant with access to Plasma Turrets or any Elite. The Knights were pretty easy to deal with despite the jankiness of their headshot hitbox. Halo 5 wasn't too hard if you didn't rush. That game was good at concealing big groups of enemies in major areas of cover. Warden Eternal was pretty ridiculous to fight, making cheesing almost the only option.