Skeletron

Skeletron is a pre-Hardmode boss encountered outside the Dungeon at night by talking to the Old Man NPC at the Dungeon entrance and choosing the "Curse" option. It appears as a large floating skull accompanied by two independent floating skeletal hands. All parts travel through blocks and attempt to make contact with the player to deal damage; each limb can be destroyed separately, but killing the head is the only requirement to truly defeat Skeletron and unlock safe access to the Dungeon.

Skeletron alternates between two distinct attack phases in a fixed cycle. In the first phase the head remains above while the hands perform slashing attacks against the player. In the second phase the head spins and chases the player, dealing substantial contact damage but suffering a -10 defense reduction for the duration of the spin (to the Classic Mode defense value where applicable). The cycle repeats for the entire encounter, with the first phase lasting roughly 13.33 seconds and the second roughly 6.67 seconds. Entering the spinning phase is accompanied by a vocal cue.

If the fight extends into dawn (daytime), Skeletron becomes enraged and permanently performs its spinning attack, gaining greatly increased damage and defense to values that make it behave like a fast, lethal adversary until it dies or despawns. Killing Skeletron during this enraged daylight state still counts as defeating it and yields its normal drops; a player who dies during the day will cause Skeletron's damage and defense to revert to normal values.

Defeating Skeletron has several persistent effects: it fully unlocks the Bestiary entry for the Dungeon Guardian, opens access to Dungeon contents (including chests and NPCs such as the Mechanic), and is required—alongside Golem—for later progression events (the Cultists that begin the Lunar Events only spawn after both have been defeated). Skeletron itself has no guaranteed material drops aside from consumables like healing potions and, in Expert/Master modes, its Treasure Bag or relic.

Practical notes and strategies:

• Prioritize destroying the hands first. Removing both hands greatly simplifies movement around the head and is mandatory in Expert Mode because each surviving hand grants Skeletron +25 defense.
• Avoid remaining far above or to one side of Skeletron for extended periods; the boss will accelerate into position and can bounce back into the player from awkward angles.
• Mobility tools are highly effective: grappling hooks, minecarts with sufficient speed, a Slime Mount, or items that allow rapid repositioning help evade both hand slashes and the spinning head. Moving quickly on a minecart can even cause the hands to despawn in some situations.
• The head’s spinning attack fires homing skulls; moving unpredictably (or jumping in a circle while using a Shield of Cthulhu or Featherfall Potion) reduces their effectiveness. Homing skulls are blocked by solid tiles, so placing a barrier can allow safe ranged/yoyo attacks.
• In Expert Mode, continuous directional movement causes most homing skulls to miss. Defensive items and buffs (for example, using a Bezoar converted via Shimmer into an Adhesive Bandage) that prevent bleeding increase the value of regeneration during the fight.
• With multiple players, set spawn points near the Dungeon so teammates can quickly rejoin after death.

Additional notes:

• The Old Man can be killed, but doing so does not count as defeating Skeletron and he will respawn at dawn if Skeletron is not defeated. Killing Skeletron after daybreak still makes the Dungeon safe. Skeletron’s sprite and cosmetic variants include seasonal or cosmetic differences (for example, the Red Hat variant which loses its hat on death), and a Skeletron-shaped cloud can occasionally appear in the background.