Water Hornet:
even if we should fail, it's still better to try and gain access to the Drakkar than no to try at all.
On the plus side, if we do fail, the resulting explosion from the barrier will kill everyone in Gazad Helkona (except Vyctar and his Nadziranim buddies) and the surrounding forest (hope the Skyrider isn't too close!)
So at least we get to go out in style! :)
For the doll, probably better for someone with Nexus to have a go at that one, thus avoiding nasty burny damage. Perhaps it could be reached by using some trick similar to the one Peacock used back at the temple to "walk on air". (Show off!)
For the pillar, that one seems simple enough to destroy. But timing is the tricky bit, would have to be really careful not to happen to score a critical hit just as you're wearing it down. Remember, the Dice Roller is EVIL!
For the idol, it did seem to be only two states. Magic Shield (Blocks magic, weak against physical), and Physical Shield (blocks physical, weak against magic). Watching it for a pattern might be useful, although there is the possibility it just changes randomly to stop people predicting it that way, also if we're on a time limit, we probably don't have the time to spend just watching that thing and timing the changes. Might need some Divination trickery.
Disrupting the runes is another possibility, but a very very risky one, as the power source for the runes is the barrier itself, and messing with that might destabilise the whole thing, and... Kaboomie!
Spider sculpture... Yep, zap it. Spiders are tiny pieces of evil anyway! >:)
Wood/metal sphere, probably easier to disintegrate that one, since it'll take too long to destroy it by just bashing away at it, or even setting it on fire. Unless someone can figure a way to safely collect and transport lava (which I can't).
(That said though... Would Kagonite be resistant to melting from direct contact with lava? Probably a stupid question, but I'll ask anyway...)