So I saw this on Twitter this morning, apparently in reference to the TV show STRANGER THINGS:
Something that completely ruined my suspension of disbelief
(scifi.StrangerThings) submitted 14 days ago by tonker
There is no ****ing way, that you would be able to kill Demogorgon with a single Fireball spell.
I haven't seen the show, but I thought this was a little extreme. So I broke out the manuals, figuring there would be three problems to deal with: magic resistance, saving throws, and total hit points.
First, magic resistance. The Monster Manual gives Demogorgon a 95%, even before saving throws; that sounds like bad odds, but it's no worse than (in fact it's the same as) rolling a natural 20. And when you read the fine print, you find that the 95% figure is for a level 11 magic user; it goes down by 5% per level above 11. So it seems plausible that the PCs might get lucky and beat that, especially PCs high enough level to get into this mess in the first place. Let's be generous in this case and say our caster is level 14 (the high end of the range for Dungeon Module Q1: Queen of the Demonweb Pits, the classic example of adventurers going somewhere they really don't belong and taking on an opponent they have no business taking on). That knocks the magic resistance down to 80%, giving the spell a 20% chance.
Next, saving throws. Saving throws for monsters are based on hit dice, but Demogorgon doesn't have hit dice, just a flat figure of 200 HP. I'm sure I've seen a rule for converting the flat figures to dice, but I couldn't find it. A quick Google suggested dividing by 4.5, which gives us 44 hit dice; other results suggested using cross-referencing the THAC0 figure in the Dungeon Master's Guide with the attack tables, in which case a THAC0 of 7 would put Demogorgon in the HD 16-17 column. (Luckily the saving throw tables flatten out at the top end, so the distinction's less important than it looks.)
Most monsters save as fighters, except … those with abilities of other character classes gain the benefit of the most favorable saving throw score.
If we want to err on the side of badass we can say that Demogorgon's spell-like abilities put him on the magic-user table at level 21+, which saves vs. spells at 4 or greater — a 15% chance for Demogorgon to fail the save.
15% of 20% gives our fireball a 3% chance of taking effect — worse than the chance of rolling a natural 20, but still not totally out of reach.
(Update: ucbpaladin points out that per Deities and Demigods, Demogorgon is a lesser god and saves at 2, which gets us down to 2%.)
We then come to damage. And here's where I have to admit Tonker might be on to something. Fireball does 1d6 damage per caster level, so for our 14th-level magic user we're looking at 14-84 points of damage, with a median of 49 points.
This is a colossal amount of damage by 1st Edition standards, and Demogorgon's going to feel it, but it's a long way short of 200.
My question, then: are there ways, within the 1st Edition rules, to amplify the damage of a fireball by 3x-4x, to get us within striking distance of 200 HP?
Best Answer
The only way to do it, with the rules as written, is to be about 100th level. AD&D1e theoretically allows this, since the experience tables are open-ended, although it was never something that was common. And, frankly, any group who kept on playing the same characters long enough would have developed some spells of their own that would be more effective
At 100th level, a Delayed Blast Fireball will do an average of about 450 points of damage, and our target's magic resistance will have disappeared entirely. Demons take half damage from fire (Monster Manual, p16), so if Demogorgon fails his saving throw, he takes 225 points of damage and croaks. If he makes his save, he takes about 113 points, and bugs out if he has any sense. The same approach will not work on Asmodeus, because devils are entirely immune to fire.
AD&D1e (and 2e) just does not have the kinds of tricks that 3e and later provide, via feats, which might let you enhance your fireball damage high enough while still being a sane level.
A spell that would let you do the job at somewhat lower level that I'm fond of is Double Fireball, which was invented by a friend who'd been reading the spell research rules in the 1e DMG carefully, and spotted the rule (DMG p. 115) on combining spells: a spell that combines the effect of two existing spells has a level of 1 plus the sum of the two spells' levels. So if you combine Fireball with Fireball, you get a seventh level spell that gives you two independently targetable fireballs, each doing 1d6/level. The commonest way to use it is to put the centres about a foot apart, thus making sure your target is in both of them, and gets two chances to fail a saving throw. This has real stopping power, and may be a bit too good for a seventh level spell, but DMs in the circles where it's used have not seen fit to ban it, since it doesn't get used often.
That lets you do seven points of fire damage per level of caster, so you only need to be about 65th level to blow Demogorgon away. I'm sure that's much more reasonable ;)