Rare keeps pushing Kameo like crack, a fifth downloadable pack will be available soon for download.

This Kameo Power Pack opens up three new co-op modes, Expert Mode, Time Attack Mode and Rune Battle Mode, which allegedly bring up the difficulty levels. From the site:

• Expert Mode: Expert Mode features six re-mastered tougher-than-ever levels, for both solo and cooperative play. Be prepared to face battles that will make even the most hardcore Kameo veterans balk. Suited up in their exclusive new Armor Skins, all ten of your Elemental Warriors will be on hand to help you in the enhanced combat…and you’re gonna need ‘em!
• Time Attack Mode: In Time Attack Mode, team up with a friend over split-screen, System Link, or Xbox Live®, and work together to try and beat the clock-and the Trolls-against seemingly impossible odds.
• Rune Battle Mode: Rune Battle Mode turns traditional Kameo co-op on its head, with new VS gameplay that pits you against your opponent-as well as Trolls-in a fight to grab the most runes. Use one of the unique new weapons to thwart your adversary in this no-holds-barred arcade scramble!

The Kameo power pack also includes 15 new achievements and a worldwide leaderboard. There’s been no price announcement so far but previous Kameo packs where about $2.50 a piece.

[Kameo Power Pack]