New strip: 1006: Uninterrupted Torment
That forced perspective makes Durkon look like he’s 18" tall 
Why wouldn’t that count as a broken-up spell?
And, as someone who hasn’t played D&D since the 80’s, is Harm so much more damaging than catching an enchanted sword full-on through the pauldron, half-way into the chest?!
Per the d20 site:
Less harmful (heh) than back in the day where it reduced a target’s hit points to 1d4 no matter how many they had. I have no idea how many hit points someone like Roy would have in this edition but he’s obviously pretty banged up.
Time for Belkar to reappear, having been saved by a deus ex machina (literally), and save Roy, losing his life in the process.
Just my WAG, of course. Rich always manages to surprise me somehow.
I think there is some kind of skill check (or feat) that allows casters to complete spells despite being damaged in melee combat.
Durkulla says he wants to hurt the world that hurt him (and he used the name Thundershield). But HE is not Durkon! He is some self willed negative plane entity, correct? Is this another misdirection attempt to confuse Roy?
It’s unclear just how the Spellsplinter Maneuver works. To be honest, we haven’t actually seen Roy do anything with it that just any ordinary warrior couldn’t do without the feat. But apparently, there’s some way for it to not work.
I don’t think that was an attempted Spellsplinter. When Roy used that feat before he did an “S” shaped swoop with his sword. This was just him striking Durkon.
OTOH, the previous time there was no special sword-swoopy.
But I notice that both times it looked like the sword wiffed and didn’t cause damage, while still breaking the spell. This time, in this strip, the sword connected. So I concur: Roy didn’t attempt a SSM.
I’ve just figured the “maneuver” exerts a static penalty on any spellcaster who is forced to make a concentration check as a result of taking damage from Roy.
Roy interrupted the spell with an attack of opportunity, forcing a concentration check equal to 16+damage dealt. This is probably a super-high number, at least 30 and closer to 40 (after power attack, strength, weapon specialization, and magic are taken into account). Durkon, meanwhile, probably has combat casting (since he’s a battle cleric) and maxed-out concentration, giving him a bonus on the roll equal to around +23 or more. My guess is Durkon rolled high on the concentration check.
Way more.
I think that was just a standard fizzle. You’ve always had a chance to interrupt a spell with an attack. As Left Hand of Dorkness suggests, I think the Spellsplinter just ups the fizzle chance to “near certain” when fighting casters who’d have feats preventing broken concentration.
Edit: On the other-other hand, Roy does nothing special when fighting Xykon although that was a dream.
A single hit from a Roy-like dude averages around 40ish points of damage, 80 on a crit*. Harm does 150 straight, or 75 if the target makes their save.
Bottomline : the worst Harm does as much as the best sword to the face.
Besides, Durkon is a vampire now, so it’s not like any of his fleshy bits are *vital *any more 
*(avg 7 on the sword itself, +5 from enchantment, +18 from 1.5x STR bonus because it’s a two-hander, +8ish from the average Power Attack gamble at these levels)
It’s worth remembering that OOTS uses D&D rules even within the construct of the “real world” so hit points matter more than visuals.
Durkon’s not even the first one to be stabbed clean through and come out relatively unharmed for it.
+18 from 1.5 str? That means he’s got a strength of 34, which is really unlikely. A super strength at his level would be something like 18+6+4+2, which means max str at 1st level (no way Roy minmaxed like that), a +6 item, all level advancements pumped into strength, and a couple of wishes sunk into increasing strength. That gets you to 30. I’d peg Roy’s probably around 24 or 26, a much more reasonable number at that level, giving the str bonus at +10 or so.
On the other hand, Power Attack could easily be higher: if Roy is 16th level, he could be doing +32 from power attack (not hitting often, but when he does, boy howdy). A power attack of +10 or +16 would be reasonable. And you left out weapon specialization’s +2. Power attack of +8 is reasonable, given Durkon’s probably very high AC.
If I were guessing, I’d guess Roy’s got a +4 weapon, doing 2d6+4 weapon +2 specialization +8 power attack +10 str, or around 31.
The concentration check would be 47, which is really really hard to make, but then Durkon has DR 10/silver and magic, and that sword doesn’t look like silver (it’s gotta be both). Now the check is 37. If he’s level 16, with a Cha of 16 (pure guess), with combat casting, he could have a concentration check of 19 (ranks) + 6 (cha) + 4 (combat casting), or 29. Maybe that’s not such a hard check after all.
It’s a +5 weapon, mentioned in-comic.
My money’s on the cat intervening.
Ah–thanks! Adjust my numbers accordingly 
I wonder if a cleric with true seeing will note Durkulas true nature and act based on this new info.
I don’t think it would make a difference one way or the other. The fact that it’s not really Durkon driving around that dwarf corpse doesn’t change the fact that the person in the driver’s seat is, in fact, the High Priest of Hel. Doing anything to put the real Durkon in control again would be just as much an interference as throwing a fireball at him.