I want to run a competitive 4E skill challenge in high-level 3E

[Noumenon]

If you're using a "skill challenge" with high level 3.5 casters, be prepared for anything. What if the wizard summons magical creatures to help with construction. Or casts Alter Self or Polymorph to transform workers into stronger creatures? Or divines who is an expert in construction and teleports them in to help?

Those don't seem truly problematic -- those are actually the kinds of awesome things you would expect 18th-level characters to be capable of and have to do to get successes in an 18th-level skill challenge. But you still require the Arcana roll to get the "success" for that strategy. Just like no matter how awesome a strategy you have for killing a monster, you still need that attack roll, you can't just describe it and have it work.

That is the kind of thing that makes me want to give +2 or +4 bonuses for spell use, though -- even if I end up adjusting the DCs so the spell use is almost required.

What if the Cleric casts Hero's Feast or Owl's Wisdom? And does the party have a Bard with them? That opens up a whole 'nother can of worms.

That is another can of worms -- spells that don't just make one character's roll succeed, but help for every roll in the whole skill challenge. Those particular bonuses aren't too huge for 18th level, but I bet there's something out there that is. For example, people could pass around magic items like "boots of springing" to make everyone succeed in a jumping-based challenge.

In a phased challenge, you could just let that be the wizard's action for the round -- you don't advance yourself to the next round, but you pretty much ensure everyone else is going to make it. Or again, just make that kind of thing necessary to hit the DCs.

 

[delericho]

That is another can of worms -- spells that don't just make one character's roll succeed, but help for every roll in the whole skill challenge. Those particular bonuses aren't too huge for 18th level, but I bet there's something out there that is. For example, people could pass around magic items like "boots of springing" to make everyone succeed in a jumping-based challenge.

Of course, to a certain extent that's a design issue. Just as there's little point in pitting a tightly-clustered group of orcs against a group if the Wizard can cast fireball, and just as you probably shouldn't pit a land-bound monster with no ranged attack against a flying group, you probably shouldn't set a group a "jumping challenge" if they have easy access to boots of springing, or the like.

For ease of adjudication, and as a rule of thumb, I would probably have buff spells give a bonus to the next roll equal to twice the spell level if it affects a single person, or equal to the spell level if it affects multiple people.

But, as I said up-thread, a lot depends on whether casting the spell represents an actual sacrifice to the character. If the challenge is one of the encounters of the day, then any spell cast comes from the Cleric's limited allotment, so should give a bonus. However, if the challenge is basically all that the party will be doing that day, then casting the spells has no great consequence (they just re-prepare them the next day). In that case, I wouldn't give a bonus at all unless the spell had a GP or XP cost - it would just be assumed as part of what the Cleric would do anyway. (In the specific example of the cathedral-building competition, it's worth noting that of course the rival team also includes high level Clerics, who are themselves also casting spells to speed their efforts.)

 

[Noumenon]

What if the Cleric casts Hero's Feast or Owl's Wisdom?

In http://www.enworld.org/forum/genera...ast-could-you-build-cathedral-18th-level.html someone suggested moment of prescience. That would really mess with the math.