Silver Arachnodrone

Located in Alcaz Island, Dustwallow Marsh. Found in an underground cell that can be reached from a sloping passage just outside the largest building on the island. In order to see it you must ensure Theramore Isle is set to its pre-destruction phase - if it isn't then speak to Zidormi on the west side of the bridge, west of Theramore. To activate the Arachnodrone you must first obtain an Electrified Key by defeating Doctor Weavil, upstairs in the largest building. The drop-rate of the key isn't 100% so you might have to kill him a few times before you obtain one, but he doesn't take long to respawn. Once activated, the arachnodrone must be reduced to 30% health before it can be tamed. Be ready to interrupt its Maximum Repair spell or it'll heal to full health.