The Giant Spider is an enemy in the Call of Duty: Black Ops III Zombies map Zetsubou No Shima. It must be killed in order to obtain the Sanguine Serum achievement/trophy. Its defeat is also required in order to upgrade the KT-4 into the Masamune.
Reaching and Fighting the Giant Spider
In order to fight the Giant Spider, the player needs to build the KT-4 Wonder Weapon. Once built, shoot the blue webbing behind the blue 115 pool to clear a path, then head into the cave. A one way slide will deposit the player into the Giant Spider's lair.
The Giant Spider is a tough boss; it has a lot of health and can only be hurt by shooting its mouth. It can stab at the player using its massive legs, downing a non-Juggernog user in a single hit, and two with Juggernog. It can spew webbing at the player, damaging and slowing the player's mobility, and it can summon a swarm of spiders within the small fight room. A Max Ammo will be dropped after every few Spiders are killed.
Upon defeat, players can approach the spider and extract one of its teeth, which is required for the upgrade process of the KT-4 into the Masamune.
Once the Giant Spider has been defeated, it is defeated for the remainder of the game. Its death will cause a portion of the cave ceiling to fall and make a bridge to the rest of the cave, where the player will find a pool of Widow's Wine, which can be drunk for free to gain the perk. Acquiring Widow's Wine this way completes the Sanguine Serum trophy/achievement.