There are a few sneaky traps hidden in the Doors of Pharros region of Dark Souls 2, not to mention some very robust enemies. Our walkthrough will take you all the way through this area safely, and leave you in great shape for the showdown with the Royal Rat Authority.
Doors of Pharros guide
All of the enemies in this region of the game are very difficult to stun, so stick to single attacks before you go into a blocking or evasive position to handle their counter-attack. You'll need to use this strategy the moment you start the Doors of Pharros, so take it nice and slowly until the first pack of enemies is dead.
Kill the huge elephant enemy, then keep walking towards the stairs until another enemy pounces. Kill him, take the large pile of Prism Stones from the corner, but don't touch the chest on the right in the water! If you do try to open it, it will come to life and attack you.
If you want to take it on, strike it with a heavy attack and then be prepared for a fight. Similar to the mimics in the first Dark Souls, the chest enemy has powerful jaws to chomp you with, except this one comes at you in a fast, scuttling motion - particularly difficult to deal with in water. At the least you'll want to light the bonfire shortly ahead, and don't try to take it on while the other two enemies are active nearby as you probably won't be able to deal with all three of them.
Go through the tiny gap in the water until you come to a bonfire. Light it, then go through the opening that's shaped like a monster's mouth. Kill the canine creature who attacks, as well as the enemy just further along. This slightly larger foe swings his weapon slowly, but he can smash it multiple times before taking a break. Don't launch your counter-attack until you're absolutely sure the attacking pattern is over.
How to kill Bowman Guthry
Once both of the enemies are dead, you'll be attacked by an Invader called Bowman Guthry. He packs a pair of meaty crossbows, but at least you don't need to be too concerned about melee attacks. When he's ready to launch a ranged attack, he'll telegraph it by raising the crossbow up. Don't let him get too many shots off without throwing some of your own damage into the mix. You need to take him down before he can make use of his Estus Flask to heal up.
"As soon as the spikes retreat back to their starting position, run as fast as you can past the danger, then kill the enemy in the alcove on your right."
When you've killed him, you'll be able to loot a Royal Swordsman Armor. Now go to the corner of the room on the far right and grab the item to add a pair of Amber Herbs to your inventory. Now take the door that's over on the far left to grab the item from the balcony above you. When you do so, you'll be rewarded with a Torch and a Gyrm Axe.
There are lots of Pharros Lockstone contraptions in this area, but many of them activate things that won't seem like much use. If you have a surplus of the stones though, feel free to experiment. There are some doors that open revealing enemies and the occasional item.
Make your way back down to the previous level, then go across the water and take the door on the opposite side. You'll be attacked by a pair of rats as soon as you do so. Kill them, then climb up the ladder over on the far side. Grab the item on your left to get hold of a Soul of a Proud Knight and a Twisted Barricade.
Kill the enemy that's just ahead of you, then carry on down this path and kill the next enemy you come to. Just after you finish this second opponent, you'll see some nasty spikes spread along the wall on your right. The sneaky enemy above you will activate this trap, but it doesn't stay active for very long at all. As soon as the spikes retreat back to their starting position, run as fast as you can past the danger, then kill the enemy in the alcove on your right.
You can open up the chest you find here, but be aware that doing so will launch a blast of poison at you. Assuming you can nullify the effects of this damage, open up the chest and take the Petrified Dragon Bone and Titanite Chunk hidden inside.
How to find the Royal Rat Authority
Carry on down the path, and then make your way around until you come to a set of stairs ahead of you. Grab the item on the floor here to bag another Pharros' Lockstone, as well as a Large Soul of a Nameless Solider.
When you go up the stairs, you'll find yourself back in the room you started off in, albeit on the next level up. Keep walking over to the left, go through the first door you see on your left, then light up the bonfire.
Don't go through the mist and into the Royal Rat Authority boss fight just yet. Instead, back out of the room you're in, carry on further along the path, kill the pack of enemies you encounter, and then go over the pair of rocky bridges. When you get over the second one, you'll see an item to the left which will grant you a Large Soul of a Brave Warrior.
Once you've picked it up, turn all the way around, head back the way you came, and then walk through the patch of mist to start the fight against the Royal Rat Authority.