Stalblind is the boss of the Thieves' Hideout, a large skeletal knight. This battle heavily relies on your merge ability and precise timing. Your sword is your main weapon.
Phase 1: Back Attack
Stalblind will charge at Link with its sword and shield. Its shield is impenetrable from the front. The trick is to wait for Stalblind to charge past you. As it does, quickly merge into the wall behind it. Move along the wall until you are directly behind Stalblind, then emerge from the wall and strike its back with your sword. After a few hits, it will collapse, and you can get a few more hits in before it recovers. Repeat this process, dodging its sword swings and charges.
Phase 2: Floating Skull & Vacuum
After taking enough damage, Stalblind will shed its armor and become a floating skull. It will then summon smaller skeletal enemies. Defeat these smaller enemies first to clear the arena. Stalblind will also perform a powerful vacuum attack, attempting to pull Link towards it. When it starts this attack, quickly merge into the wall to avoid being sucked in. After the vacuum attack, it will be vulnerable for a short period. Emerge from the wall and strike its skull with your sword. Continue this pattern until Stalblind is defeated, rescuing Gulley and obtaining the first Lorule Sage.