The Apocalypse is the best weapon with attack of 597 and boosts HP up to 403. In order to get the Apocalypse greatsword, you need to complete the full story campaign.
After that you need to get the Dungeon Seal Key by completing the specific dungeons. Once you have got the key, you need to take on the quest called A Menace Sleeps in Balouve.
After taking the quest, go to the Balouve Mines dungeon. In the dungeon, you will come across the boss whom you need to defeat.
The enemies here are level 75 so if you are lower in level make sure to use some legendary weapons. Near to that place you will find a small gap in the wall, in which you will find the secret dungeon door.
Enter inside and keep going until you come across Apocalypse. You will find it on the floor at the first camp site which is found 5 floors down to the place you are right now.
Cheat Codes
Enter a battle and take a substantial amount of damage. Then, find a spot to teleport and regenerate your HP and MP it has to be one where Noctis basically hangs there with his sword. Execute a companion technique while you are regenerating your HP and MP (Prompto's Stinger works well). When the short QTE for the follow-up strike occurs, execute it. You have to not have fully regenerated your HP and MP by this point for the exploit to work. HP and MP regeneration will now keep happening until you end the game or load a save. Note: This glitch was performed on an unpatched version of the game. It will probably eventually get patched. To avoid not being able to use this exploit, either do not install new patches before using this exploit or delete the patches. You can avoid patches being installed by disconnecting from the internet until you are ready for the game to install new patches.
How to Get Infinite HP And MP
Take some damage from enemies on purpose.
Warp to a 'Point Warp'.
When you are regenerating, use a technique.
Now the Point Warp regen effect will stay with you even outside battle.
Note that this bug will go away if you restart the game, load a new game or fast travel long distances.
Infinite AP
This exploit allows you to get 1,000 AP every 30 minutes. First, have the following items and the Armiger Action Ascension Node:
Armiger Accelerator: Included in the paid Holiday Pack DLC.
Blitzer's Fanfare: Included in the paid Holiday Pack DLC.
Shield Of The Just: Found in the Royal Tomb, west of the Disc, in Thommel's Glade.
Warrior's Fanfare: Included in the free Holiday Pack DLC.
Once you have those items and Ascension Node equipped, complete the following steps:
1.Go to The Three Valleys and find the area where a pack of dogs spawns.
2.Use the Whistle Command to summon enemies.
3.Wait until Battle Mode activates, then use Warp Strikes to kill the dogs.
4.Immediately after killing the dogs, activate Armiger Accelerator. This gives you +1 AP. Wait until the battle is over to activate it or you will deplete Armiger.
5.With the "Warrior's Fanfare" and "Blitzer's Fanfare" activated, you will get +3 AP for defeating enemies with A+ Timing and Offense. This require good timing with Warp Strikes - so it may take some practice.
6.As soon as the +AP number appears, whistle to summon another pack of dogs. If you do not summon immediately after the pack is defeated, you will have to wait until the report card is complete.
7.Repeat this process as many times as desired to earn an unlimited amount of AP.
Note: This exploit works after Patch 1.03. To avoid not being able to use this exploit, either do not install new patches before using this exploit or delete the patches. You can avoid patches being installed by disconnecting from the internet until you are ready for the game to install new patches.
Quick Tips
Items are very important in the early game so stock up on Potions, Elixirs and more.
Use Elixirs to replenish your maximum HP after dropping into a Danger state.
Take cover behind objects to replenish HP and MP.
If you Warp (Triangle or Y) to a higher vantage point you will replenish your MP.
Use the Wait combat mode and press and hold R1 or RB to determine a target's strengths and weaknesses.
Don't forget to check the Ascension menu when you have AP in order to learn new skills for Noctis and his friends.
To use magic spells you need to craft them in the Elemancy menu.
If you're doing a lot of running, turn on the Stamina bar in the Options menu.
Stop by every diner and talk to the person behind the counter to add new locations to you map.
Talk to the diner manager to accept hunting quests for XP and gil.
Various Steam Achievements
Complete the indicated task to unlock the achievement.
Achievement
How to unlock
A New Blademaster
Scored 1,000,000 or more points in Score Attack.
A New Protagonist
Unknown.
A Noble Sacrifice
Unknown.
A Way Forward
Unknown.
Altissian Ambassador
Collected all documents.
An Emperor Deposed
Defeated the kaiser behemoth.
Angling Expert
Reached maximum fishing level.
Angling Rookie
Improved fishing level for the first time.
Another Path
Unknown.
Beacon of Hope
Powered up all facilities in Lestallum.
Beacons of Hope
Completed the Comrades quest with all four characters.
Black Mage
Used magic for the first time.
Blessed by All
Collected all the Royal Sigils.
Blind Spot
Performed first blindside link.
Brother-in-Arms
Issued first ally command.
Callings
Unknown.
Chocobo Jockey
Rode a Chocobo.
Chocobreeder
Raised a chocobo to Level 99.
Chosen King
Unknown.
Cleaving a Path
Unknown.
Column Colossus
Uprooted all columns.
Come Back, Kenny!
Met the owner of the Crow's Nest Diner.
Cooking Expert
Reached maximum cooking level.
Cooking Rookie
Improved cooking level for the first time.
Dark Clouds
Unknown.
Departure
Unknown.
Divine Intervention
Summoned one of the Six for the first time.
Dogged Rider
Earned the top ranking on all three Time Trial courses.
End of Days
Unknown.
Faithful Heir
Unknown.
Field Photographer
Took 10 photos mid-battle using Selfie Shot.
Hidden Power
Took down 10 enemies using the spelldaggers.
High Five for Justice!
Played JUSTICE MONSTERS FIVE for the first time.
Homecoming
Unknown.
Immortal Photobomb
Unknown.
In the Dark
Unknown.
Insomnia's Waking Nightmare
Unknown.
Just Hangin' Around
Performed first point-warp suspension.
Kingly Blessing
Received a Royal Sigil.
Learner's Permit
Drove the Regalia.
Let There Be Light
Unknown.
Living Legend
Unknown.
Love Turned Tragic
Unknown.
Magical Worker
Crafted a spell for the first time.
Maiden Voyage
Unknown.
Master and Pupil
Performed 5 link-strikes with Cor.
Master of the Elements
Took down 100 enemies using Total Clarity.
My First Hunt
Completed first hunt.
Narwhal Watching
Unknown.
New Power
Learned first ability.
No Pain, No Gain
Scored 500,000 or more points in Score Attack.
No Turning Back
Unknown.
Noct You Like a Hurricane
Initiated first link-strike after parrying an attack.
One with Your Blade
Crafted a weapon of Level 30 or higher.
Party of Three
Unknown.
Photo Expert
Reached maximum photography level.
Photo Rookie
Improved photography level for the first time.
Picker-Upper
Picked up all items.
Pursuit of Knowledge
Filled 80% of the Datalog.
Quadruple Threat
Equipped four weapon slots.
Redemption
Unknown.
Regalia Pilot
Unknown.
Royal Retinue Rumble
Unknown.
Seaworthy
Unknown.
Seize the Moment
Performed 10 full-hit cross chains.
Self-Improved
Activated 20 ability nodes.
Self-Mastered
Activated 50 ability nodes.
Sharp Shooting
Took down 30 enemies with crackshots.
Shield of the Chosen King
Completed the trials on Normal.
Speed Daemon
Posted excellent times in all cross-country test drives.