Devil May Cry Nightmare Boss
Difficulty (DMD): 
Location: Mission 16, Mission 18 and Mission 20.
Nightmare Profile
Nightmare can be a tricky adversary, as he constantly has you running through hoops in order to weaken him. He starts off in his liquid form which is invulnerable to all of your attacks. You must force him to transform into his solid form by damaging the large symbols scattered around the outside walls, which will turn the lights on, and with Nightmare being evil and what-not, he’s not so keen on the light. Once he is weakened and turns into his solid state he will reveal his core, which is your cue to unleash a flurry of attacks while he is vulnerable, but be quick as you are only granted a short space of time before the lighting expires and he returns to his invincible liquid form. At this point you will have to repeat the process over. Try to keep an eye open for his multiple stabbing attack in this form, they can reach pretty far but provided you are lively on your feet you should be able to dodge them.
You may notice that your devil trigger gauge will quite often be sapped by Nightmare, which he will occasionally use to transform into his own devil trigger form, increasing the power of his attacks. Equipping Ifrit is recommended for this fight as the techniques you can use will dish out a fair amount of damage to Nightmare’s core. Please note however that your newly acquired Nightmare Beta weapon will be rendered ineffective against this boss.
Comments and Discussions
At present, a total of 3 comments have been posted.
this is of no help because I already knew that but I can’t beat him still
Attack the switch before the battle starts, so that you don’t have to deal with the puddle at the beginning. Use Inferno when his core is revealed - otherwise, run in a circle around him to dodge his attacks. When he melts, either let him swallow you, or put him back in armored form. If you can’t use an inferno, go ahead and attack him with ifrit or alastor anyway.
Inside of him, use jump+shotgun+ifrit to take out the skulls, then take out the inner boss as usual.
For the final battle, use Air Raid instead of Inferno. If he gets you in the net, use DT Alastor to slash at one of the bigger cords, and get out from under him.
It’s pretty simple, actually.
I find that Alastor wth/ Ebony and Ivory combo is best for this fight. Air Raid is necessary, so much so if you dont have it, you will struggle so much more to complete.
The best way to get prepared for the first battle is before you enter the fight, go back along the Long Corridor, killing all Marionettes, then go back to the Aeroplane Room with the Plasma, kill him (using Ifrit) for loads of red orbs, then return to the Corridor and kill the marionettes. Keep doing this until you have enough to buy a vital star, as many devil stars as you can, yellow orbs, a couple of holy waters and Air Raid. Make Air Raid the priority,
The easiest way to kill him is when you start the fight, let him swallow you straight away. This will take you down into his stomach and (making sure you dont have to use that vital star) kill the sargasso using the shotgun and then Phantom/Griffon/Nelo Angelo. One of the sargasso and then the mini-boss should drop health and plenty of red orbs, before you return to the surface. The reason for being swallowed is when you cut your way back out, it drains a quarter of his health and every little helps.
Its probably best to reequip the handguns while down there.
When you return, light a switch asap.Shake the left analog stick and jump to get rid of the nightmare worms. Use the handguns while jumping around like a kangaroo on steroids to inflict as much damage to the core as possible, and as soon as you have Full Devil Trigger (its advisable to have at least 4 for the attack to be most effective), use it and use Air Raid as soon as you press L1 pretty much. The attack puts you higher than 99% of Nightmare’s attacks and inflicts a helluva lot of damage to the core. When Trigger runs out, try and land on his back to slash with Alastor before you fall off.
His attacks are very limited.
1. When in liquid form, if you get too close he will bite you, asing you in ice. A: DONT GET TOO CLOSE
2. When in liquid form, he will send worm-like things to case you in ice so he can bite you. A: Wiggle the Left Analog Stick and jump to avoid their attack which can be damaging when in numbers.
3. When solid, small probes that fire at you are ejected. A: VERY EASY, just continue to jump and fire with your handguns, they will auto target onto them and destroy them.
4.When the core is shown, sometimes Nightmare releases its captured souls at you. A: Medium, if you let them adamge you, it hurts ALOT, but as long as you can hide and fire until your fingers hurt, you should be fine.
5.When seriously damaged, red electricity will conver his body. A: This can hurt you lots, so dont land on him once this appears.
6. When the core is exposed, he will fire a large white beam from his head and in later fights will spin this. A: His msot damaging attack by far, avoid at all costs. This attack is the reason behind many retrys i had. The telltale signs of this attack is the small white bolts he fires just pre-beam. As soon as you see these, jump and roll and jump. If you have it, use Devil Trigger and Air Raid.
All of this should mean you can beat him and nothing much really changes in the following fights, except in the last fight, where once you kill the core, it revives another 3rd of health from somewhere. Still using the guns to gain trigger and air raid to use it, this still kills him relatively quickly
hope this helps ppz (and Mital who seems a bit stuck)
peace x