Master of Masters difficulty is unlocked by completing every stage on Master Samurai difficulty. Unless you want to be tortured, I highly recommend completing the game on both lower difficulties first before attempting Master Samurai difficulty. Patience is key as this is a grind. During these playthroughs focus on getting collectibles and unlocking the entire skill tree.
Each difficulty adds more enemies as well as upgrading them to their stronger forms. Enemies and bosses now have more health and do more damage. You will also occasionally run into more miniboss fights on higher difficulties. By the time you get to Master Samurai you should be able to handle it with patience, with a few snags along the way.
The biggest barrier In Master Samurai was Aku's tower for me as I attempted It with depleted resources. I got all the way up to Aku himself and got my ass kicked so I had to exit the stage and farm resources. My method was completing Aku's Tower on Jack difficulty and stocking up at the shop each time. The following items are what I prioritized:
-Having all healing items, strength and defense potions maxed
-Buying all projectiles each run through the tower (minus the bullets). Bomb arrows will be helpful.
-Repairing any weapons that need repaired.
-Buy the heroic guardian bracelet and make sure you equip it when fighting regular enemies. Buy the heroic power bracelet for boss fights.
I also made sure I had the Great Samurai Warrior sword. You can follow this guide to unlock it.https://www.ign.com/wikis/samurai-jack-battle-through-time/H...
I ran through the tower around 4 times before I felt I had enough items to attempt the tower on Master Samurai. You don't need to complete the whole stage, just make sure you get an autosave before restarting the stage. Going in well stocked I was able to spam bomb arrows to clear a lot of waves which allowed me to save my healing items. Bomb arrows work well on the ninjas, who are by far the worst enemies in the game. Alternatively your Samurai fist combo works very well against ninjas (more details on this combo below). I made sure to save all three charges of my kiai fire for Aku. When I got to him I used a strength potion, changed bracelets to power, switched to my Great Samurai Warrior sword and used all three of my kiai fire attacks on him and finished him in one cycle, thus unlocking Master Of Masters mode.
Now that unlocking Master of Masters mode is out of the way, you should be ready to grind through this mode. Being well stocked before each stage will be the rule of thumb going forward for this difficulty. Always stop at the shop and top up on projectiles and healing items during this playthrough, as well as repairing your weapons. When you feel you are getting very low head back to Akus Tower and stock up at the shop a few more times.
There are several different weapon playstyles, so its hard to give my opinion on each one. Obviously if your weapon of choice is comfortable and working use it, but if the weapon doesn't seem to work on certain groups of enemies its time to change things up. User A Batwomen Today suggested using the samurai fist:
Samurai fist are pretty much what I used for all of it. There's a broken combo. It's circle the analog left stick and Y to do a spin move your invulnerable at times and also I used LB and Y when enemies attack and going ham on the X or y buttons you get a couple or seconds to freeze time. I also used a lot of arrows or throw Weapons when I needed space or on flying enemies.
I think this move does help a lot especially around those annoying Ninjas, but I do find myself taking damage a lot and wasting healing items so at times I recommend playing defensive and using projectiles to save on health items.
Here are things to note for each stage:
Stage 1: The first wave will throw in the annoying slug enemies. Stay up on the stairs above them and use your shurikens to snipe them safely. By the time you get to the swamp area will you encounter a copy and pasted mini boss fight with Demongo. Expect to see a lot of him in this run. Make sure you save all three charges of your kiai attacks before fighting the boss as he has a lot of defense this time around. Switch to your GSW sword, your Power pendent, potion up and spam your kiai special three times to easily beat him.
Stage 2: Use your shurikens to beat most of these enemies from a distance. Don't go out of you way in this stage and focus solely on the objective. Shortly into the stage you will fight Demongo in addition to many waves of enemies. Use your kiai attacks wisely and spam projectiles to make this room easy. Once outside, there will only be a few required waves of enemies, whereas most you can run past. Take advantage of your high jump move as there are several spots I found that could jump and skip sections of the mountain. Again conserve your kiai for the boss. Use your potions, power pendent, GSW sword and spam your kiai and the boss will go down quickly
Stage 3: Other than addition waves of enemies and an extra Demongo fight, this stage is mostly routine at this point. The biggest hiccup for me was the boss fight. This time he has additional enemies in this fight which caused Jack to focus on them when I used my first kiai attack, wasting it. Take them out with projectiles first then use your potions and spam your specials on the boss with your GSW, killing him easily.
***Now might be a good point to stock up on items at Aku's Tower
Stage 4: Ninjas are spammed all over this stage making it a huge pain. Bomb arrows seem to work well but you will go through them quickly in this stage. Luckily there are plenty of shop locations in this stage so you should be able to make it to the boss will all healing items stocked. This boss was a huge pain. She spams ninjas and other enemies making the fight ridiculous. When shes on the ground potion up and once you have a good shot use your kiaia specials on her. I hit her all three times and it only did about half her health so I found myself spamming her and her endless waves of ninjas with bomb arrows until finally I managed to defeat her. Be prepared to use a lot of resources in this fight.
***Highly recommend stocking up at Akus Tower before the next stage.
Stage 5: Several of the sewer fights are skippable so run past them. To fight the imakandi I recommend using a kiai attack with your sword. Don't worry about saving your kiai attacks for the boss so use them when ever there are multiple ninjas or imakandi on the stage. For the 2D section before the train use piercing arrows and they will easily beat the enemies there. For the boss fights on the train I recommend using the Morning Star weapon or Samurai first comb along with piercing arrows. Not much strategy beyond that, but make sure you grab Josephine's umbrella when her health is low using your barefist for a quick kill option and an achievement.
Stage 6: This stage is a huge pain. The first Demongo fight really messed me up as he spawns three ninjas at a time. They block most hits, execute insanely deadly combos that are hard to block and are quicker than your dodging attempts. Use the samurai fist combo here if you want to cheese them, otherwise expect torture. The first golem fight is nothing special, but the second one has an additional Demongo fight in the same arena. Luckily ninjas aren't the only enemies spawned so they are both manageable. The boss was also a pain for me. Immediately take out the annoying ranged enemies so they no longer spawn. For whatever reason weapons seem to instantly break for me during this fight so using your GSW only during kiai attacks. It is critical to maximize your damage output each cycle and the boss only stays around for a limited time. I was at a disadvantage because I only had one kiai charge going into the battle, but using three should do at at least 25% health per charge. The hardest part will again be the infinite ninjas that spawn, which bombs or samurai fist should manage to hold them off. The boss will only jump down once one ninja is defeated, and will only have a max of three per time in the arena so its possible to kill one and leave the health low on the other two so only one new ninja spawns per cycle.
Stage 7: Ashi's sisters go down pretty easily with the Samurai fist combo. The biggest threat in this stage seems to be managing your healing items. If you fight a wave of enemies and find yourself needlessly wasting healing items you can also quit to the main menu and continue from the last check point and try again. Feel free to use kiai attack whenever you need to in this stage as the samurai fist is more than enough for the boss. The last room before the boss has an additional Demongo fight which isn't too bad and the enemies gave plenty of kiai to tear through this room. When you have the final showdown with Ashi's sisters spam your fist combo, focusing on one at a time. I also found jumping and pressing Y to be useful against them. Nowhere as near as tough as stage 6 thankfully.
***Highly recommend stocking up at Akus Tower before the next stage.
Stage 8: This stage surprisingly wasn't that challenging. Use your samurai fist combo to win this level with little struggle. Jack's fists work pretty well on the mini bosses so don't sweat them. Do save all three kiai attacks for Ashi. Like previous boss fights, maximize your damage using potions, your power pennant, your GSW sword and then unleashing all your kiai attacks in succession on Ashi. Each did about 25% of her health, but I was lucky and managed to get extra kiai during the first three rushes so I quickly finished her off with a 4th charge.
Stage 9: This difficulty added a lot of enemies that use projectiles. Counter them with your own projectiles from a distance. For larger waves of melee enemies use your bomb arrows and when you narrow down the arena use your samurai fist combo. Theres also a golem battle now which isn't that bad. Just remember to save your three kiai attacks for Aku. I maximized my damage and used all three in a row dealing 75% of his health. I then finished him off with bomb arrows, but reapers work just as well if you have those. Oddly enough not one ninja spawned for me in this difficulty, but I imagine they are on a timer and I killed him before any could spawn in.
And with that you beat the most difficult part of the game. Overall not too bad but will take patience. Happy to see they added a secret ending as well so make sure you watch that if you skipped it in previous runs.