If it’s a weapon, I’d guess a hammer for a cleric of Thor - IF Burlew does something as conventional as a weapon. 
I’d bet on something off-the-wall, and something fleetingly mentioned in the strip yonks ago.
I can give you that Durkon is probably better than Hilgya and Minrah, you could at least expect him to make his will save. But what they had in that fight was even better: a completely unexpected high level divine caster that the other side did not know about or plan for. In a vampire fight that’s much more of an advantage.
I’d suspect that they’d actually do better in a similar fight against Xykon. Xykon is largely a two-man show (three with MitD but we don’t know enough to say how that’d affect things). D&D action economy heavily favors the side that can make attacks at a 3:1 ratio. Xykon & Redcloak are powerful but they still only make one attack (or cast one spell) per round. OOTS lost the vampire fight because Team Vamp had five clerics casting Dispel Magic and then throwing out “Save or Suck” Dominates.
And, honestly, it was more improbably deus ex machina that nearly everyone failed their Will saves than nearly anything that’s happened in OOTS’s favor so far.
Edit: Out of curiosity, I read the section on dwarves in my old 1st edition AD&D Player’s Handbook and nothing jumped out as useful. Unless you want to count the rule that dwarves never use magic and are restricted to being fighters or thieves 
I still think it’s a possibility though since the strip references the 1st edition Unearthed Arcana as where Tarquin learned drow sign language.
Another point with Xykon is that, thanks to O-Chul’s one-save-at-a-time intelligence gathering, they know exactly what he’s capable of, and can take specific preparations against each of his spells. And even if he does dispel their protections, that’s his entire round’s worth of actions, there, when he’s already behind on the action economy.
Yes, there are some pretty serious divisions on team evil, which is what the Order will be wanting to exploit. Both Xykon and Oots aren’t keen on ending the world. Redcloak doesn’t have a problem with apocalypse, but just might be susceptible to diplomacy. (Fast talk not so much.) I don’t know whether MitD is good (O’Chul demurs) but I don’t think he’s evil.
What swirly-eyed spell did Xykon cast on MitD, and how binding is it? What precautions could a hypothetically patient goblinoid take if he had a lot of time on his hands to ponder matters? How could Oots protect Redcloak from Xykon, once the true purpose of the rift spell is revealed?
Also, the battle royale might include O’Chul and Lien, currently on a stakeout near the North Pole. One would hope: they are quite likeable.
And any fight with O Chul on one side it unbalanced by its very nature. He is, quite possibly, the toughest damn person on the entire planet.
Redcloak can cast both Resist Fire and Death Ward, both of which have long durations, and both of which he’d be almost certain to have prepared and pre-cast on Ritual Day (because they both know that they’re going to betray each other the moment the ritual is finished). Between just those two spells, Xykon’s offense is almost entirely neutralized. Meanwhile, he can also cast Heal and Disintegrate, both of which are quite likely to work and which, between them, should be enough to finish Xykon off.
Basically, if Redcloak wins initiative or gets a surprise round in a one-on-one fight, he’d have an excellent chance of beating Xykon immediately, and even if he doesn’t, Xykon would only have a chance to get off one spell to stop him.
Meteor swarm. We’ve seen him do it.
And, ADHD as he is, he’s pretty solid on coming up with interesting ways to use magic to deal with problems. I wouldn’t put it past him to come up with useful ways to use things or to have some invented spell or item that works unexpectedly.
The fight wouldn’t necessarily be unbalanced. O-Chul has amazing stats but they’re focused on defense; he’s incredibly hard to kill. But as an offense fighter, I believe he’s merely above average. Roy, Haley, Belkar, and Vaarsuvius are probably all better at inflicting damage on an opponent.
I’m not so sure. If it comes down to a fight, Xykon has a ring that protects him against positive energy (and Redcloak knows it) so Heal will have no effect. (Interestingly Redcloak has Tsukiko’s Ring of Negative Energy Protection, and Xykon likely (but not certainly) knows it.) And Xykon is an Epic spellcaster with Superb Dispelling, which could remove many or all of Redcloak’s protections, as it did with V. Superb Dispelling would really ruin Redcloak’s day. Xykon also has a high Concentration skill so even Disintegrate might not phase him. Disintegrate also has to hit and Xykon has many protections. Any fight is going to be a close one.
The game-changer, though, is that Redcloak has Xykon’s phylactery and he doesn’t know. How will Xykon react to news of that?
You’re right about that. Mind you, how would Xykon find out? Redcloak is the only one who knows. Odds are he’ll only find out the next time he’s destroyed and doesn’t end up on the Astral Plane.
O-Chul can be what kids these days call a “meat shield” or a “tank”, absorbing damage while the others strike back.
Every paladin can pile on a decent amount of damage with smite evil too.
Meteor Swarm does a whole lot of damage in a fairly large area, but it’s also very easy to defend against if you know it’s coming. Since it does its damage in four separate blasts, resistance is very effective against it, and a Resist Fire spell would almost completely negate it.
I was counting on Xykon’s first action being Superb Dispelling, but he’ll probably only get at most two actions before Redcloak finishes him. Which means that he’s only got one shot to finish Redcloak, and it’s tough to take out a high-level cleric with one shot.
He probably does have a very high Concentration skill (though I’m not sure if that’s ever been demonstrated), but that’s irrelevant to Disintegrate: Redcloak wouldn’t be trying to distract him; he’d be trying to kill him. For that, he’d need a fortitude save, and undead have terrible fortitude saves.
And if he ever had a Ring of Positive Energy Protection in the first place, he doesn’t any more. The Order looted the rings off of his body when they destroyed him in the Dungeon of Durokan, and that wasn’t among them. I think the consensus is that that was just a bluff.
As for O-Chul, meatshielding isn’t very effective when dealing with sapient enemies, because they’re just going to choose to attack someone else instead of you. And he’s probably not high enough level as a paladin to even have a mount (most of his levels are in fighter), so his Smite Evil would do, like, +4 damage, once a day. Yeah, if he’s there and wants to help, you accept gratefully, but he wouldn’t be that big a deal. At least, not in combat. Where he is likely to make a big difference is in influencing Monster-San to side with the heroes.
That’s one potential game changer. The other one is Xykon’s secret mind control of the MITD to attack Redcloak if Redcloak betrays Xykon.
Start of Darkness is where he claimed to have a ring of positive energy protection, yes.
He showed it to Redcloak. Is there any reason to think that the ring he was wearing was not a Ring of Positive Energy Protection?
I guess I did pick a bad time to get back into this.
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