The Watcher

"Congratulations, you made it through the Entrance. I have been watching you closely...Unfortunately, for now, this is the end of the road. I sense many dead spirits eager to return to the living..I will bring some of them back. Watch this."

- The Watcher (Catacombs Entrance)

The Watcher is the  of Catacombs Entrance of The Catacombs Dungeon. He also appears in all the following floors, acting as a  players must defeat before moving on to the main boss of the floor.

Necron has a close connection to The Watcher, calling it 'The Eye', with them mentioning it in their welcome speech.

Lore
Stalker

This strange creature is roaming The Catacombs to add powerful adventurers to its collection.

The Fight
The Watcher will summon undead spirits from the display cases on the walls. Players can not directly damage the Watcher and must instead kill all the spirits in order to win the fight.

Players who are dead when the fight starts or die during the fight are reanimated as a hostile Wandering Soul that resembles the player who died. Killing a Wandering Soul will revive the player it resembles.

The Watcher will stop summoning spirits after a while. Be wary that the spirits are very tanky and can last a lot of hits. Players win the fight after they have defeated all the spirits, as the Watcher itself cannot be damaged. If you attempt to attack it, it will say something like "I am not your enemy." or "Stop attacking me." and zap you with a laser, dealing high amounts of damage.

This fight gains new mechanics at later floors.

Arena
The Watcher's arena is fairly simple. There are 4 chains in the room with the Undead's heads on the wall. There are some corridors behind the Undead wall. A way to cheese the boss on the earlier floors is to go on top of the portal, entrance door, or go on the second layer of the Undeads. Keep in mind the top of the exit portal changes on every floor.

Floor 2
Starting from Floor 2, the Undeads gain special perks unique to their type.

Floor 3
During Floor 3, Bonzo is reanimated at the start of the fight. There are some distinctions between Bonzo during this fight and during his debut in Floor 1. Bonzo doesn't revive and he will instead have 300,000 health instead of his original 250,000.

Floor 4
On Floor 4, the watcher will be next to 2 Watchful Eyes, which deals heavy damage if a player decides to try to camp the Watcher. Scarf also has a chance of being reanimated instead of Bonzo.

Floor 5
All mobs spawned by The Watcher gain a random modifier:
 * Speedy increases the mobs' speed, and gives a chance for the mobs to drop Dungeon potions on death.
 * Stormy allows the mobs to strike lightning on nearby players, and gives a rare chance to drop Thunderlord VI Enchanted Books on death.
 * Healthy increases the mobs' maximum health, and gives a chance to drop Healing Tissues on death.
 * Boomer makes the mobs explode on death and drop Superboom TNT.
 * Stealthy makes the mobs invisible except for their name tags and armor.
 * Golden makes the mobs drop Gold Essence on death.

The modifier will be announced before the fight begins. For example, when Boomer mobs are summoned, The Watcher will announce "These will be stubborn and unwilling to change!" before the first summon.

Floor 6
The Watcher no longer announces the modifier of its summons before starting.

Livid has a chance to be reanimated instead of Scarf or Bonzo. Upon death, Boss-type undeads have a chance to drop their respective Fragments, which can upgrade items related to them. For example, Bonzo Fragments dropped from Bonzo can upgrade the Bonzo's Staff and Bonzo's Mask.

Floor 7
At the beginning of the fight, before Bonzo, Scarf or Livid is summoned, one of Sadan's giants (The Diamond Giant, Jolly Pink Giant, Bigfoot, or L.A.S.R.) will be reanimated. The pillars will be removed in the arena, making space for the Giant. Each one has a chance to drop its respective Precursor Relic, which can upgrade gear dropped from Necron.

Battle Hints

 * If The Watcher says "You'll do.", "This guy look like a fighter." [sic], "Let's see how you can handle this.", "Go, fight!", "Hmmm... This one!", or "Go and live again!" he will summon a spirit.
 * Look at the display cases on the walls. You'll get a general idea of how the fight's going to be. Note that the Watcher will only summon some of the spirits in the cases.
 * Once The Watcher says "That will be enough for now." he will no longer summon spirits.
 * The Watcher is immune to Arrows and other ranged projectiles. Hitting him with one will deflect it and will make him shoot you with a laser.

Strategies

 * The Watcher is easily cheesed if one camp by the walls, the pillars, or the portal doorway of the room. This only works up to Floor 3 because Floor 4+ have Watchful Eyes shooting lasers at you if attempting to camp on higher ground.
 * Floors 2 & 3 also have ways to prevent cheese, with Psycho teleporting up to you on Floor 2, and Bonzo's Balloon Barrage on Floor 3.
 * For Floor 4+, it is possible to camp outside the blood room to prevent the player from getting swarmed.
 * If you're very weak to tank the Undeads, use an Aspect of the Dragons to knock them back and use a range weapon to clear them out without being touched. However, at the release of Floor 6, all of The Watcher's Undeads have magic knockback resistance.
 * If you use a Spider Pet and Frozen Scythe, you can potentially permanently freeze them before reaching the Blood Door to not get swarmed.
 * It is best to send a class with high area-of-effect damage, such as the Mage, to clear The Watcher's mobs. This is due to the high number of enemies.
 * More advanced players may opt to enter a Floor 6 or 7 run solo, rush to open the Blood Room, kill the reanimated Giant and boss, then exit the dungeon. This technique is known as "Frag Running", and is very lucrative as certain drops from those mobs such as Livid Fragments are valuable.

Loot

 * On defeat, he will drop 2-3 dungeon blessings.
 * Blessing of Life
 * Blessing of Power
 * He can rarely drop Optical Lens.

Trivia

 * Despite the name similarities, The Watcher has nothing in relation to a Watcher in the Dragon's Nest.
 * In the Journal, The Eye, it is shown that The Watcher was related to Sadan's interest in Necromancy.
 * The Watcher's eye resembles the Eye of Cthulhu from Terraria.
 * The Watcher will revive a player when their Wandering Soul was killed.
 * The color of The Watcher's eye starts changing from a vivid green to a sickly yellow the deeper you go in the Catacombs.

Quotes

 * "You have failed to prove yourself, and have paid with your lives. You will make an excellent addition to my collection." -If you have failed
 * "You have proven yourself. You may pass." -If you have won
 * "I am not your enemy" - If a player attacks the watcher.
 * "Stop Attacking me" - If a player attacks the watcher.
 * "Don't make me zap you" - If a player attacks the watcher
 * "Ouch, just kidding..." - If a player attacks the watcher
 * "We're always watching. Come down from there!" -If a Watchful Eye catches you
 * "Don't try to sneak anything past my Watchful Eyes. They see you up there!" -If a Watchful Eye catches you
 * "A Wandering Soul? Poor Guy." -If a Wandering Soul is summoned.
 * "A Wandering Soul? Don't you guys have a Healer?" -If a Wandering Soul is summoned.
 * "Oof." - If a Wandering Soul is summoned.
 * "Oops. Wasn't meant to revive that one." -Upon summoning an undead.
 * "This one looks like a fighter." - Upon summoning an undead.
 * "You'll do" - Upon summoning an undead
 * "Let's see how you can handle this" - Upon summoning an undead.
 * "Go, fight!" - Upon summoning an undead
 * "Go and live again!" - Upon summoning an undead
 * "Hmm... This one!" - Upon summoning an undead.
 * "That one was weak anyway." -If an Undead summoned perishes
 * "I'm Impressed." -If an Undead summoned perishes
 * "Not bad." -If an Undead summoned perishes
 * "Very nice." -If an Undead summoned perishes
 * "Aw, I liked that one." -If an Undead summoned perishes
 * "Welcome back to the realm of the living, (PlayerName)" -When a player revived by The Watcher
 * "So your name is Sadan, I see..." -The Watcher to Sadan in The Eye
 * "Ah, you've finally arrived. I have watching you closely since we last met. I don't know if you are ready for what's behind this door. So I will decide if you are strong enough." -Welcome Speech on Floor 1
 * "Ah, we meet again... I have done some experiments to develop new abilities for my Skulls. Let's see how you handle this!" -Welcome Speech on Floor 2
 * "So you made it this far... interesting. You are much stronger than I was expecting. Not to worry, I recently added a very fine piece to my collection!" - Welcome Speech on Floor 3
 * "You've managed to scratch and claw your way here, eh? Don't even think about trying to outwit me this time! My Watchful Eyes are keeping their ...eyes... on you!" -Welcome Speech on Floor 4
 * "I'm starting to get tired of seeing you around here... This time I've imbued my minions with special properties! These will {Status Effect}" -Welcome Speech on Floor 5('be quick and agile!' for Speedy, 'be adorned in the finest gold!' for Golden, 'be healthier than any summon I've ever created!' for Healthy, 'be kinda hard to see ngl.' for Stealthy, 'strike thunder from the sky!' for Stormy, 'be stubborn and unwilling to change!' for Boomer)
 * "Oh... hello? You've arrived too early, I haven't even set up... Anyway, let's fight... I guess" -Welcome Speech on Floor 6
 * "Things feel a little more roomy now, eh? I've knocked down those pillars to go for a more... open concept. Plus I needed to give my new friends some space to roam..." -Welcome Speech on Floor 7