Here's an example of the sort of Skill Challenge I run with my group all the time - This is pretty much exactly how it's written up and handed to the Players (this one was used during a modified WoTC adventure).
It may not suit everyone, but my group loves them and we use them often -
COMMANDEERING THE HELM SKILL CHALLENGE
(XP: 2000)
You have finally located the Helm of the Blade of Al’veydra – the Planar Ship Connor Reyar used to navigate the Astral Plane! But, you’ve discovered that it is already operational (Zirithian “started it” to open the portal to Tytherion), and perhaps worse, you’ve realized that in order to make the most of the Helm, it requires a unique and distasteful fuel: living souls!-THE CHALLENGE-
It is important to know that from a game mechanics standpoint, the Helm functions pretty much as described in the Manual of the Planes – in conjunction with a vessel that has a Navigation focus, it acts as a locus for a Plane Shift ritual that will move the vessel and its occupants to any plane already visited by the “navigator” (as per the ritual). Although the ritual can move the ship to an unfamiliar location, the results can be random at best.
However, there are two unique aspects to Connor Reyar’s Helm: One, with either sufficient Anarch (a secondary fuel source) or living “soul” energy, the vessel can travel to the Elemental Chaos. Second, it appears able to travel through time, at least in some fashion, as well (more research can unlock this).
Prior to your arrival, Zirithian clumsily used the Helm to punch a hole to the plane of Tytherion: he’s been fueling the Helm with Drow in Cozule (thus, all the Undead Drow running around), but since the Helm was used while “unseated” (i.e., not in a vessel with a Navigation focus), it has created the random side effect of the Planar breaches, or slips, that currently roil through Cozule.
Now that you’ve found it, you can wrest control of the Helm from Laareen/Zirithian, and because of the unique nature of its current operation (at the moment, the Helm actually occupies a “space” between both the Prima Material Plane and Tytherion), you can refocus it toward a place anyone in Fellbane is familiar with – Al’veydra.
If you succeed at the Skill Challenge, all of Fellbane and the Helm will transport fully onto the Prime Material Plane (subject to the Plane Shift Ritual; i.e., an Arcana check will determine how close you get to your intended destination), closing the door to Tytherion behind you as you go!
“Commandeering the Helm” is a Complexity 3 Skill Challenge (8 Successes before 3 Failures), that can be accomplished as outlined below: As battle rages around you, a PC must sit in the Helm and attempt to control it and direct it. Getting in the Helm is a Minor Action, staying there throughout the battle is a whole other matter…!
The Zirithian Counter
Also, at the start of the encounter the Zirithian Counter is set to 4: That is the number of rounds before Zirithian (and perhaps someone else?) comes through the Portal to defend Laareen and the interests of Dal-Morvrey. Every Primary Skill check moves the counter +1 round, any failure moves it -2 rounds.
The Primary Check
The Primary Skill check is Arcana (DC: 25, Standard Action). All checks can be accomplished by the same PC.
Secondary skills are: Religion (DC: 20, Standard Action; You understand that the Helm is fueled with the necromantic energy of Souls. Limited to 2x. The first success unlocks the Soul Engine additional action; the second success unlocks the To Live & Die in Cozule additional action. Note: You can use up both Religion secondary checks for the same Primary check!), Arcana (DC: 20, Standard Action: You understand that the Helm can possibly be “retuned”, albeit briefly, for Radiant energy. Limited to 1x. This success unlocks the Heaven and Hell additional action), History (DC: 15; Standard Action; You know the unique history of the Helm, making it easier to comprehend and exploit. Limited to 2x). A successful Religion, Arcana, or History secondary check adds +1 to the Primary check, plus the additional consequences listed above, if any.
All Secondary checks must be conducted adjacent to the Helm.
Additional actions: There are other ways to affect the Primary Arcana checks.
• Soul Engine: Every power with the Necromantic keyword expended into the Helm adds to the Primary check. An At-Will adds +1 to the Primary check, an Encounter adds +3 to the Primary check, and a Daily adds +5 to the Primary check.
• To Live & Die in Cozule: Up to two (2) PCs adjacent to the Helm can voluntarily subject themselves to five (5) ongoing damage to add +1 to the Primary check. If they are not adjacent to the Helm at the start of the turn when the Primary Check is made, they do not take the damage and do not get the bonus. Any living creature killed adjacent to the Helm adds +5 to the Primary check, and negates the possibility of a critical failure. If a PC voluntarily sacrifices himself to the Helm, you gain two complete Successes toward the challenge (and the PC returns as a Revenant, as per that Class write-up).
• Heaven and Hell: A successful Arcana Secondary check has revealed that the Helm can be “retuned”. This takes two (2) Rounds, during which time no Primary checks can be made (although the Zirithian Counter continues to move), and during each of those two (2) Rounds a Daily power with the Radiant keyword must be expended into the Helm. At the end of this process, the Soul Engine additional action is altered to the following: Every power with the Radiant keyword expended into the Helm adds to the Primary check. An At-Will adds +1 to the Primary check, an Encounter adds +2 to the Primary check, and a Daily adds +4 to the Primary check. The To Live & Die in Cozule additional action is also altered to the following: Every living creature adjacent to the Helm who “donates” a Healing Surge (as a minor action) adds +1 to the Primary check. Note that retuning the Helm allows the Primary Arcana check to be substituted with a Religion check (DC 21, Standard Action). However, if there is any Round during which no Radiant energy is “poured” into the Helm, it reverts back to its Necromantic focus.
Taking Damage
Whoever sits in the Helm trying to control it will probably be the target of numerous attacks. Sitting in the Helm grants Combat Advantage, and further, any damage taken by the Navigator prior to the Primary check for that Round adds a cumulative -1 penalty to the Primary check…
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Success: Every two successful Primary skill checks adds a +1 cumulative bonus to the Skill Challenge and moves the Zirithian Counter as noted above. Every failed Primary skill check garners a -1 cumulative penalty to the Skill Challenge and moves the Zirithian Counter as noted above. If you’re successful at the challenge, the Helm and anyone you designate Planar shifts to the place you’ve directed (subject to the Plane Shift ritual), and the doorway to Tytherion closes!
Failure: If you fail this challenge, the Helm shuts down completely for an undetermined time…and you will probably be neck deep in combat…
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WHAT ABOUT “AID ANOTHER”?
You can do one Aid Another attempt (DC: 10 plus half level, Standard Action) per Primary check. The PC attempting the Aid Another must be adjacent to the Helm.
ADDENDUM – THE DROW COUNTER
Depending on how you’ve dealt with Zaknoril at the time the Skill Challenge begins, you may be facing a Drow Counter as well (this adds +750 XP to the Challenge). It will start at six (6) - the number of Rounds you have before Matron Urlvrain’s forces make a run at Laareen. This number inexorably counts down -1 each Round of the Skill Challenge, and is only affected if you fail one of the Primary Checks by five (5) or more. If you do, it goes down -2 for that Round…
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Again - it might not be for everyone, but I use this template over and over. Players can always suggest additional Primary and Secondary skills, and I always provide the chance for the Players to use Magic Items and Powers to help them through the challenge...