In Jagex's own words:

• Ten times the chance to win super-rare cosmetic items!
• More coin prizes added that will also appear more frequently, including 5,000, 50,000 and 500,000gp!
• Coin prizes substantially increased in value, e.g. the 50gp prize is now 1000gp.
• More useful common items in increased quantities.
• New items swapped in to replace your most commonly discarded items including:
  • Construction and Fletching supplies such as planks and logs.
  • Crafting and Smithing materials, including leather and ore.
  • More gems, from sapphire to diamond.
  • Combat consumables such as arrows and runes.

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