Make four seasonal outfits, then combine them into the ever-fresh threads of the Armour of Seasons.
From 23rd of June at 00:00 UTC until 27th June at 23:59 UTC Treasure Hunter will yield four types of natural material: flourishing seeds, lush blossoms, fallen leaves and charred branches.
These can also be collected through Skilling too: by training Herblore, Woodcutting, Farming and Firemaking, respectively. You can also get your hands on materials of any of the four types by trading directly with other players.
Collect 600 of a particular kind of material to create its outfit. When you have made all 4 outfits, combine them to create the full Armour of Seasons.
Any spare materials will be cleared up on 11th July, but before then you can trade them for Bonus XP in their related skill by speaking to Lady Niya who is located south-west of Varrock, near the Champions' Guild.
The full Armour of Seasons is tradeable, should you wish to trade it.
Ironmen can collect materials and make the outfits but cannot trade any of the promotion's items and cannot convert them for bonus XP with Lady Niya.
What does the Armour of Seasons do?
The armour of seasons will automatically change its appearance, based on the date, to match the seasons of the northern hemisphere. This can be changed to match the southern hemisphere by right-clicking the armour pieces and choosing 'invert'.