Maggot King

Maggot King is a free private solo boss with no quest requirement. Enter through the boss teleport list. The fight begins behind a bone wall, so bring ranged or magic plus a melee weapon for the punish window.

Fight Mechanics

After a screech, the King changes between ranged and magic. Do not leave a protection prayer active through the screech: doing so causes damage.
Ranged attacks leave poisonous bile. Magic attacks leave sticky bile that drains a combat stat and delays attacks.
Larvae appear while the fight develops. Kill airborne larvae with ranged; landed larvae crawl toward you, leech on contact, and heal the boss.
At about 65% health, wall slams begin. Step out of the three-tile-wide lane. Protect from Melee reduces a slam if you are caught.
After a slam, click the exposed head to Strike it with an empowered melee hit.
Below 20% health, repeated slams make movement the priority.

Choose the Corpse Reward

Only the eligible killer can claim the corpse. You must choose one route:

Open-stomach: main-table roll. Base unique chances are Elder venator fang 1/100, $100 scroll 1/80, Crimson kisten 1/60, and $25 bond 1/30. The Maggot Marquess is a separate 1/3,500 roll.
Take-eggs: rolls one of six egg types with supplies or nothing; it does not use the Open-stomach pet roll.

An Elite clue may roll from either choice. After claiming, the boss begins its short respawn.

Aranei

Aranei trades venator fangs and teeth one-for-one for dragon arrowtips and dart tips. Give her 25 mixed tarnished items for one hour of +25% Maggot King reward chances. That service has a two-hour cooldown. The boost improves the relevant unique chances; it is not a universal boost to every reward.