Create the opening with defense, spend it on a short burst, then reset the arena before greed creates the next hit.
Confirm the fight is actually unlocked
Hearing the Goblin King mentioned is not enough. Find the Goblin Hideout is earlier in the chain; Hoard King's Fall and the objective to collect Tamsin's explosive are the stronger signal that the boss stage is next.
Reset at the Sanctum before entering
Start with healing and combat-item charges restored, Nourishment filled, unnecessary inventory cleared and any affordable upgrade already applied. Do not begin an open-ended perfect-gear farm when a clean resource reset solves the immediate problem.
Rest before recrafting
A current community report distinguishes rest from cooking: a world campsite can rest at any time, while the Sanctum tent is reported to be night-only. Both can replenish combat consumables such as potions and elemental flasks, so use the sequence unload → rest → cook food / prepare cures → enter the arena instead of automatically remaking every item.
Let the King commit first
The reliable pattern is to read the heavy swing, then parry when the timing is clear or Dodge when it is not. Use the recovery window for your highest-value status or spell sequence, then disengage before a long animation turns the punish into a trade.
Manage the added goblins
Extra goblins are dangerous because they interrupt movement and split attention, not just because of their individual damage. Keep room to move, use area damage when available and remove the extra pressure before committing to another long single-target sequence—unless the King is already one safe punish from dying.
Use potions as a build diagnostic
If every attempt consumes the same healing before the King reaches a familiar phase, change the loop rather than only adding levels. A rematch is useful evidence: fewer potions and cleaner counter windows show a real improvement, even without a damage spreadsheet.
What happens after the kill
Return to Corin and continue the forest storyline. The Goblin King is a campaign milestone, not the current Early Access ending; the main route continues toward the Forest Throne and Aelwynor.