Turns out we can change difficulty on the last level for GrandMaster...

[Eispan]

... unlike on the Original PS3 version, we can quit the game and still be able to come back to continue where we left off on the PS4 Enhanced Edition.  The game autosaves all the stuff as we pick them up or collect and it also automatically remember the last level we were at before logging off. 

 

So to cheese our way out of a full Nightmare playthrough just play on Normal until the very last level - just right before the Warlock's lair.  Leave the game and make a backup to a USB pen drive or to the PSN Cloud as a fallback in case we screw up and die. It is much better to redownload a good backup save to replace a failed one, rather than play the game from the very top of the abyss just to try again. 

 

Upon returning, just continue with the game until we reach the the option to turn on Nightmare mode as well as Friendly Fire in the setting settings - both are required to be set to ON for the trophy.

 

The next part is up to us... if we came in prepared then everything should be a breeze, nothing to worry about.  There will be three enemies - one big Warlock and a mini Warlock one will appear as well as random Nightmare Hero to join in the final battle.  I had brought the Pendataur Knight to be the first tag with a complete set of (4 max) health vials.  Having the mana bar in full will  help tremendously, so make sure it is also full before jumping into the boss lair.

 

There you go, Nightmare mode made easy with just one level to play for.

 

 

Edited August 20, 2022 by Eispan
GrandMaster easy peasy...

[Thermopyle2]

This tip is very helpful, thanks. I've been sitting for years with this incomplete but now I'm going to make another go of Grandmaster. What level were you when you beat it? 

 

An additional tip:

If you find one of the good shrines (shows a statue of the characters you can switch between, and looks like a fist symbol on the map) and you are low on health for either your character OR your summon, clear enemies between the nearest trap and the shrine, then drop all your items (weapon, equipment, soul, and consumables) and kill yourself on the trap. Pick all the items back up as the soldier, then return to the shrine to revive and switch back to your hero. Your hero AND the summoned soul will be back to full health.

 

The cost is your mana (you start back at 0 after dying), but with full health for you and your soul without having to use potions that's a good trade-off, IMO.

 

The reason to pick up the items as the soldier is because this is the only way to restore your summoned soul's health. If you revive your character and then return to pick up your gear afterwards, the soul will not have its health restored. 

 

[Thermopyle2]

I just did it at level 49. Got lucky and found an easy map at the 2nd to last spot, so backed up that save, loaded back in with a nightmare difficulty switch. It also had a good shrine so I was able to ditch all of my stuff, die, pick it back up as the soldier, and then go into the boss fight with no mana but full health on Pendatuar Knight and on my hero, along with 1 large health and 3 medium. I used up all the health but ended the fight as the Knight without ever having to switch. 

[Eispan]

Sorry for the late reply... I believe I was Level 30-ish when I faced the final boss.  It also helps when we get a treasure room before we reach the final two levels.  We can use the same reload trick to fill up or replenish our Mana and HP vials/stocks to max for the boss fight.  The maps or routes that will be given to us at the start as we all know is RNG.  Getting a very good route is a huge factor to get this done faster as you have mentioned.

 

Good thing I played the PS3 version first.  Had I first experienced how better the Enhanced version is, playing the original PS3 version would have felt like a downgrade and huge chore.

 

 

Edited January 11 by Eispan
... still both versions are great to play.