[D&D4e] Critique my Skill Challenge
I am about to running The Demon Queen's Enclave for a group of 14th level PCs. I am hoping to open with a combined dream sequence Skill Challenge. The PCs best skills are around +20. Their trained skills are roughly around +15 and untrained normally around +10.

Signs and Portents

Goal: The PCs receive a myriad of signs and portents of the future and a rising evil. However, these are not merely the stuff of dreams but ripples from the Realm of Dreams. The PCs must try and glean what information they can from the maelstrom with their sanity and courage intact.

Complexity: 3 (8 successes before 3 failures)

Encounter Level: 14

Initiative: The PCs act in the following order (being an Initiative based on Wisdom).

Aid Another: A PC may forego their turn to aid another PC instead. If this is done, then only the PC making the roll gains the success. Also, when that reroll is used the PC who aided is dazed (save ends) as their mind is jarred by a dreadful sense of déjà vu of what they saw.

Skills Used:
• Arcana (DC 20, maximum of one success): You know the stuff of dreams is dangerous, but also malleable. You can shape the raw elements of dream to your advantage. You also gain a +2 to all further rolls in this Skill Challenge.
• Athletics (DC 25, maximum of three successes): You meet the ferocity of the dream with a ferocity of your own, smashing your way through the tendrils that try to bond you.
• Endurance (DC 25, maximum of one success): Buffeted by the gruesome forces arrayed against you, you simply grit and endure it.
• Insight (DC 18, maximum of two successes): You see right through the obfuscating and confusing symbols and images that confront you into the truth of the matter.
• Intimidate (DC 22, maximum of one success): You face the sense of growing dread with a stalwart determination to vanquish it.
• Perception (DC 18, maximum of one success): You avoid distraction of the weird and wondrous around you and notice the one true image that tries to evade you like
• Religion (DC 20, maximum of two successes): Contact from beyond this world is something you are familiar with, and you take comfort in your faith.
• Stealth (DC 25, maximum of one success): Surrounded by nightmare you become one with it, dancing out of sight like a mad god.

All other skills are available at DC 28. Each skill is maximum of one success.

Success: For each success, the PC who made the roll gains a reroll that can be used at any stage in the adventure. If the reroll is made then the results of the second roll must be kept.

Failure: For each failure, the DM may force a PC to make a reroll that can be used at any stage in the adventure. If the reroll is made then the results of the second roll must be kept.