As you earn supply crates inside the prison, your loadout will shift naturally toward bonus-granting alternatives. The premier set is the Pyromancer outfit. Each individual piece grants an experience bonus: 0.4% for the hood, 0.8% for the garb, 0.6% for the robe legs, and 0.2% for the boots. Equipping all four components triggers an additional set bonus of 0.5%, lifting the total Firemaking experience gain to an effective 2.5% boost.
Slayer training opens another functional warm item: the Lit bug lantern. Requiring 33 Slayer, this unpretentious lantern sits in your off-hand slot. Pairing a Lit bug lantern with an axe held in your main hand frees up four other equipment slots for Weight-reducing Graceful gear if you plan on doing high-agility supply runs across the northern camps.
For accounts that already secured rare drops, the Tome of fire offers an unmatched utility slot. Obtained as an untradeable drop from Wintertodt supply crates (or bought empty on the Grand Exchange), it acts as an unlimited source of fire runes while equipped in the shield slot. Crucially, it registers as warm gear even when uncharged with burnt pages.
If you prefer to chop with your highest-tier Woodcutting axe in your main hand, wielding a Tome of fire or Bruma torch alongside Warm gloves and Clue hunter trousers caps your cold protection without sacrificing your main weapon slot.
