Kirk, Knight of Thorns is an NPC invader that will constantly invade as a Dark Spirit and attempt to kill the player. A former member of the Darkwraith covenant, Kirk is now a Chaos Servant attempting to collect humanity for The Fair Lady by killing those who have it. Kirk will invade a total of three times in different locations, if players wish to gain his armor, sword and his shield, they must defeat him all three times. In order for his invasion to trigger, the player must be human, and the boss of the area must be alive.
Kirk will invade the player for the first time in the depths, so The Gaping Dragon must still be alive. He will invade the player near the area in which the Basilisk (the curse breathing frog demons) are found. He is not a hard fight as long as players are smart with attacking and defending. After killing him, he will drop the Spiked Shield, the Barbed Straight Sword, both or neither; and about 4,000 souls.
Kirk will then attempt to invade and kill the player again in the Demon Ruins. To trigger this invasion, the player must be human, have killed Ceaseless Discharge (to drain the lava) and to have played the Lordvessel down on the altar. Kirk will spawn just after the first Capra Demon but the actual invasion will not start until the player has walked at least halfway down the staircase. Same fight as before, just be mindful of the very large fall into a pool of lava. He will drop yet again the Spiked Shield, the Barbed Straight Sword, both or neither; and about 4,000 souls.
Kirk will attempt to invade the final time just outside the Bed of Chaos boss room, in the same place where the hollowed pyromancer is located. The player must be human and the Bed of Chaos must still be alive. He may yet again drop the Spiked Shield, the Barbed Straight Sword, both or neither; and about 4,000 souls.
After defeating Kirk all three times his armor can be found on a corpse in Quelaag's Domain to the left of Quelaag's Sister. If the corpse is not there, reload the game.