Easier Boss Rush mode
Activate the Devil Soul and use the Valmanway Sword. You will take down all the Bosses in less than five minutes.
Defeating Abaddon
When fighting Abaddon, equip Death as your Guardian Soul. Death's scythes will attack Abaddon repeatedly for about 30 to 35 HP of damage per hit. Death's Soul also will destroy some of the locust swarms that Abaddon uses. Keep dodging Abaddon and the locust swarms, and use Mind Ups or Mana Prisms to keep your MP filled. Use potions or food when your HP gets low. When using a combination of physical attacks and Death's Guardian Soul, it will not take long to take down Abaddon.
Defeating Aguni
Aguni is arguably the hardest Boss in the game. He has four attacks; a downward spiral that explodes into large pillars of fire, three smaller fire pillars, a swoop attack, and repeated slashes with his claws. To dodge his attacks, keep as far away as possible, or extremely close to a wall. When he swoops past or comes to swipe at you, duck underneath and slide inward. His pillar attacks can be dodged by jumping, and often open up for easy hits with a heavy weapon (for example, Great Axe or Mjollnjr) . Some helpful Souls that can be used include: familiars, Corpseweed, Barbariccia and Erinys.
Defeating Dmitri
If you have a Witch Soul, let Dmitri copy it. The projectile attack from this soul is fairly easy to avoid and will make this fight a lot easier.
Use Une on him and let him copy it. It is the easiest enemy skill to avoid. Also, be sure to not use any R skills (especially the familiars), as he will also copy them and use them along with the bullet skills, giving him two attacks which you must avoid.
To defeat Dmitri in your first encounter with him, use the Axe Armor bullet-type soul only, because any other soul you use will be copied and used against you. Use the Axe Armor until you hit him once. He can now only use that attack. When he uses your Axe Armor, go in-between the attack and himself and hit him with any heavy weapon once. He will then dash backwards and attack you again. Repeat this trick until he dies. Do not get worried if he hits you with the Axe Armor, because it will not hurt much.
The best way to defeat Dmitri is to use the Cave Troll Soul and let him copy it. The Tongue will go to the end of his arm.
Dmitri is the easiest Boss to kill, even with very few Souls. All you need is the Flying Armor and some Mind Ups (High Mind Ups are recommended). Every time Dmitri tries to strike with the Malachi Soul, jump over the bullet, then hold [R] to use the Flying Armor and hover over. The Malachi Soul forces your opponent to stop temporarily while you shoot. This is an opportune time to use normal or magical weapon attacks on Dmitri. Magical weapon attacks do approximately double their normal damage, but this varies on the weapon. If you run low on MP, use Mind Ups accordingly.
Alternatively, in Boss Rush mode, you can use Succubus on Dmitri. If you are lucky enough to hit him, you can successfully dodge him for the rest of the fight, as Succubus only lunges you forward slightly, but pulls you back greatly after use. This makes it easy to deal non-MP-based attacks on him.
Hit him with your best Soul first, then either Cave Troll or Axe Armor. Then, switch back to your best Soul. He will keep using his current Soul if you start using a Soul you hit him with previously.
Defeating the Iron Golem
Use the Imp soul. It switches HP damage to MP damage.
Easy Mothman
Use the following trick to get Mothman to appear easily. First go to Yoko then go to weapon synthesis. Synthesize the hammer to its last stage (Mjolln Jr.). Note: You will need to sacrifice a Boss soul in order to do this. Then, go to the Pinnacle and go to the room that has the two final guards. Use the weapon on the generator. This should make the Mothman appear.
Defeating Puppet Master
Use a familiar against the Puppet Master and have him attack the dolls the Puppet Master summons. By doing this, you can proceed to attack the head while the familiar takes out the hands. Note: For this to work, you must have extremely quick reflexes and great hand-eye coordination.
Attack faster
If you have a heavy weapon like a great sword, slow attacks can be a problem. To hit the enemy twice quickly, stand very close to them and attack. Then just as it connects, press [L] to dash backwards. As soon as it stops, you can attack again; and if you are still close enough it should hit. This is quicker than just attacking twice normally.
Julius HP recovery
Find an Imp, then change to Yoko. Let the Imp posses her (make her attack). You should regain HP with each attack. Note: The Imp may choose to attack you; make sure you have enough HP to survive one or dodge it if the creature lunges.
Easy Boss Rush mode
Have Kaladbolg, Serenity Robe, Chaos Ring, Slogra, Gaibon, and Stolas Souls on Equip set A and Black Panther Soul on set B. This gives you very good Int and the ability to throw multiple high damaging spears. Gaibon Familiar throws a spear when you throw one. You can quickly go through Boss Rush mode, approaching the two minute mark.
Easy damage
Get the Medusa Head Soul from Subterranean Hell and activate the Malphas "Double Jump" ability. At the peak of your double jump, hold [R] to use the Soul and press [Down] + [B] to activate a downward kick. With [R] held, you will stay afloat, yet gain speed as if you were actually falling from a high peak. This combination can deal one- or two-hit KOs to many strong monsters (for example, Treant or Alura Une) when [R] is charged, and can take down powerful Bosses in as few as five hits.
Alternatively, using certain bullet/guardian combos can yield very powerful results. Using Bullet Souls in conjunction with a high-level familiar can make for a powerful damaging combo. Other combos that yield great results are:
Frozen Shade [B] / Quetzalcoatl [E]: Create blades of ice in front whelk Quetzalcoatl goes in for the kill. This is effective against single-file enemies.
Malachi [B] / Gergoth [E]: Throw Malachi's shadow orb to continually damage your foe while shooting Gergoth's beam.
Succubus [B] / Catoblepas [E]: Freeze your opponents in stone, then do double damage while regaining health.
Last two abilities
The last two abilities are actually enemy souls. These souls are the Procel and Mudman. Procel is found in Subterranean Hell. whereas Mudman is found in the Abyss. These souls allow you to walk through water and sand freely.
Secret Monsters
There are three secret monsters (the Yeti, Mothman, and the Flying Humanoid.) To get the Yeti you must first get the Waiter Skeleton Soul then go back to the very beginning of the game. You will see him walking in the background. Toss the curry and he will come up where you can attack him and gain his soul. You will need the Rycuda soul leveled up to at least two to get Mothman. Go to The Pinnacle to the area where there are two final guards and a light in between them. Strike the generator next to the light with Rycuda and Mothman will appear. For the Flying Humanoid, you will need the Mandragora soul. Enter the room in between the Zephyr Boss room and a save room then use the soul.
Easy Soul Eater Ring and money
Get the Mimic soul and go to the Clock Tower. There is a save room with a spike pit next to it at the bottom right corner of the Clock Tower. The Mimic soul will usually give you 500 gold each time you are hit by the spikes. Whenever you get low on health, go to the save room, heal, and repeat.
Bell
To get the bell you need to get the Hippogryph Soul in the abyss. Go to the room in the dark chapel with the three bells and use the Hippogryph Soul under each bell. One of them will drop the bell that you can sell to Hammer.
Crown
In the Demon Guest House, there is a small room with a bed, a waiter skeleton, and a chair in it. When you walk in, the skeleton will throw curry at you and run into the wall, killing itself. Walk in front of the chair and press [Up] to sit in it. Wait for about fifteen seconds and a crown will appear on the floor in front of you. It cannot be equipped and you cannot use it. The description reads "5000 points".
Double Archer
Set Amalaric Sniper soul as a Bullet soul, then set Skull Archer as a Guardian soul. Whenever you go to charge the Skull Archer with [R], the Amalaric Sniper will automatically activate at the same time and fire alongside. This is a very powerful combo, especially in the early levels, as how most enemies are not strong and will die quickly. Also note that depending on how long you charge the Skull Archer's soul, it may consume a lot of mana.
Gold Ring
To get the Gold Ring, go to the room in the Subterranean Hell containing the gold door with the slot machine. Have the last three digits of your gold to be 666 and the door will open, revealing the Gold Ring. This makes enemies drop more gold.
Iron Golem Soul
In your sets, equip in A: unarmed, your favorite armor, and Soul Eater Ring. In the Souls, equip Imp[B], Black Panther[G], and for enchant, you can use anything. In set B: use any weapon, your favorite armor, and Chaos Ring. In Souls, equip Succubus[B], and any other guardian and enchant, though Treant[E] is recommended. Then, go to the place in Wizardry lab where you break the ceiling. Find the fountain in the lost village, then fall all the way down, and turn right to find the Iron Golem. Activate Imp[B], and punch the thing very fast and it should die. If you get low on HP or MP, use the Black Panther[G] soul to dash to the room on the right, then switch to set B. The Chaos Ring will replenish your MP and you can use the Succubus[B] soul to get HP from the ghosts. When the process is done, switch back to set A and continue fighting the golem.
Konami man
In the Clocktower in one of the rooms with a lot of spikes, there is a small area with no spikes that is very difficult to reach. Use the Bat Company Soul and land on the spot, then crouch. The Konami man will fly by, which you can catch and sell to Hammer.
Shaman Ring
In the Condemned tower, there is a room with a gold slot machine door. Make the last three digits of your gold to be 573, and the door will open, revealing the Shaman Ring. This allows you to gain experience faster.
Three 7's clothing
In the Garden Of Madness is one of the gold slot machine doors. Have the last three digits of your gold to be 777. The door will open, revealing the three 7's clothing. This will boost your Luck, Intelligence and Constitution by 7.
Free potions
In one section of Subterranean Hell you will notice a see-saw with a boulder sitting on it. In the background are bells hanging on the walls. Hit the flat part of the see-saw with a hammer type weapon. The rewards for ringing the bells are as follows:
First (lowest): Potion
Second (middle): High Potion
Third (highest): Super Potion
Soul Synthesis warning
If you want the best weapons in the game, be ready to give up some of your Boss souls. For example, if you want the Claimh Solais then you must give up the Gergoth soul.
Easy money
Go to the Lost Village. Kill some Axe Armors until you get an axe. Then, go to Yoko's house and upgrade the axe into the Battle Axe. Then, upgrade the Battle Axe into a Bhuj. Then, go to Hammer's shop and sell it for 10,000 gold. If this is your first time in this level, then you should save the money. After you have played a few more levels, you can buy good weapons such as the katana, handgun, etc.
Easy experience
Equip yourself in the A set with Dracula's Tunic or Demon Mail, Gungner the Last Spear (recommended due to its reach and does not lose important souls) or Valhmanway Sword, and the Shaman Ring. In the Soul part, equip the Imp soul in Bullet, the Black Panther in Guardian, and the Mothman in Enchant. In set B, have all the same except for the Chaos ring, the Succubus bullet soul. Go to the large falling trail near Lost Village (in front of Yoko's shop there is an entrance where you blow up the ceiling in the fountain). Then, go to the end. Go right there and you will see an Iron Golem. With set A, use the Imp Soul and the weapon you selected to kill him faster. When you run low on magic, change to set B with [X] and replenish fast with the Chaos Ring. If you run low in health, use the Succubus Soul to get life from the ghosts on the right and replenish. Go from right to left (from the ghosts' side) with the Phanter soul to go faster. Kill the Iron Golem to get 3,500 experience points each time.
On your equip, have any weapon, any armor, and the Shaman Ring. On your souls equip, have Dead Mate, Black Panther, and the Mothman soul. Then, go to the Wizardry Lab were there are lots of Merman in a room. This is after you pass the big spiked room. Use your Dead Mate soul to kill the Merman and leave the room. You will easily gain about 3,000 experience points. Continue to use this method to level up quickly.
Pass the spiked room
In order to pass the spiked room that is in Subterranean Hell, you can use one of these methods. The first is to equip these souls: Puppet Master, Bat Company and Skeleton Ape. Fly up until you get to a space on the floor with Bat Company. Then, use Puppet Master so you can transfer to the next space. Fly again with Bat Company to the other side. The second method is to equip on your R souls, Bone Ark. Then just use it from the start of the spiked room and wait for it to carry you the next end.
Glitch: Leave level boundary
This trick requires the Succubus Soul and the Cutall weapon. Go to the last save location in the Abyss and do the special attack on the very end of the wall, not near the door Keep doing the special move until you fall out of the level. You can get back to the save room. If you have a 100% map completion, you will uncover about 56% more if you manage to get back in the save room. Note: If this is done, you will make the final Boss impossible to defeat. After you defeat him, he will just respawn.