Scion said:
Although you put forth actual numbers, even though the comments seem to ignore what I have said in my last post, I will talk about what you put forth.
You posted your numbers before I finished writing mine. A
So, a character with 20+ ac and 40+ hp can withstand at least 4 barages. Since the character in question does indeed have a 20 ac and 40+ hp (couple of good rolls, it happens) then that means he can take the single aoo, get up and go face to face for up to 3 more rounds.
How many hit points over forty? Unless it's 45, your math is off. With a 20 AC, he'll be unconscious after the hydra's second action. (15 (AoO)+15 (normal attack) +15 (normal attack)=45).
In any event, it appears that your "modified" standard array is pretty dramatically modified if your party fighter has significantly more than 40 hit points and a 19 strength.
19 strength at 4th level means he started with an 18 and probably put the stat bump into strength at 4th level or he's a half-orc and started with a 16. Point cost: 10-16.
40+ hit points is possible with a 10 con but that would require rolling three tens. With a 14 con (typical point standard array fighter), he needed to roll 22/30 in order to get even 40 hit points. That's 75%. In order to get 45 hit points (leaving him staggered, but conscious to make the final swing), he would need to roll 90% of his possible hit points on the dice. There's less than a 1% chance of that happening. If he's a barbarian, the hit point total is more understandable, but his AC is unusually high. (16 dex, +1 breastplate, and +1 ring of protection would get him there--until he raged--but now we're talking about a character who spent a minimum of 26 character creation points on strength, dex, and con--32 points unless he's a half orc).
At which time his high str plus power attack will allow him to do well over 20 points of damage a round against such a low AC. (if he power attacked enough and got lucky he could kill the thing in one round, but that is a bit beyond normal probability)
It's got 55 hit points and an AC of 15.
So, assuming no rage (because that would drop his AC and make him die more quickly), your 19 strength fighter type will probably have an attack bonus of +10 (+4 BAB, +4 str, +1 weapon focus, +1 weapon) and does an average of 16 points of damage per hit (2d6+6 str +2 weapon specialization, +1 weapon). Without power attacking, he hits on a 5 so he deals an average of about 13 points of damage per round. If he power attacks for full, he attacks at +6 for 2d6+17 and therefore deals an average of 14.4 points of damage per round.
Either way, without fast healing, your fighter would still take an average of four rounds to kill the hydra--that's two more rounds than it will take to kill him.
Add in the Hydra's Fast Healing
15 (I misremembered the number before) and every round, the hydra will heal almost all the damage he does to it. If he doesn't have help, he's toast.
The only way he could possibly kill it in one round would be to move up, power attack for full, crit, and then proceed to roll 21+ points of damage on 4d6...and have it fail the massive damage save. Otherwise, it heals 15 points of damage and still survives to attack him that round. You're right to say that that is "beyond normal probability." (10% chance to threaten*60% chance to confirm*0.6944% chance of rolling 21+ on 4d6*25% chance of it failing the massive damage save=.01% chance of that happening).
This is useing no help from the party other than the marshals abilities.
Assuming that the druid would be willing to cast barkskin on him beforehand (not unlikely) and the cleric to cast an aid (which is in his domain spell list)
The barkskin would help as would Aid but Shield of Faith would help more than Aid.
and the rogue to tumble and flank then this hydra is going down in no time (sure, the rogue couldnt take more than 5 attacks, but he would then just have to tumble out again, and that one round of an extra +2 to hit plus the hit from the rogue pretty much spells the doom of this critter.
Um. No it doesn't. The hydra's still going to be there by round 3 whether or not the rogue hits. If the fighter does 20 points of damage per hit and hits in rounds one and 2, by the end of round 2, the hydra will still have 45 hit points left (fast healing 15 is nice). If the rogue does 20 points of damage, the hydra will still be able to take another hit from the fighter. And if the fighter misses, he'll basically have to start back from the beginning.
So, with minimal loss (a couple of spells, one of which is decently long term for 3.5, and some hp) the party of 4th level characters took out the beast. The melee brute himself could stand toe to toe for awhile, and if he got lucky even defeat it singlehandedly.
So, with an immense loss of hit points and some unusual luck, the party will take the beast out. There is about a 1/1000 chance that the melee brute will take out the beast singlehandedly. (The beast's chance of taking him out on the AoO is much higher than that).
That is 'with' the 5 heads per aoo, without then the battle wouldnt even have been even that interesting
Again, I have stated it was in the game I am in several times, since the rules are unclear then playtesting is a good enough place to look at.
With a single round to prepare a 4th level party would seem to have a pretty incredible chance against this guy, easily defeating it with minimal losses. Sure, there is a chance of horrific failure, but then that is how it is for most/all pure melee beasts (check out the giant scorpian).
With a bit of preparation, I don't dispute that a 4th level party could defeat the hydra but I seriously doubt it would be "with minimal loss." All of the odds are against that. The chance of horrific failiure is (as explored above) somewhat higher than the chance of incredible success.
This guy generally isnt intelligent enough to do very complicated things, he is incredibly slow, and has no ranged attack.
He's as fast as the fullplate armored fighter and can full attack at the end of a charge. That's slow but not that slow.
[/quote]A single ray of enfeeblement will take most of the bite out of this battle (or at least has a good chance to -6 makes his attacks all only +3 and deal d10 damage, hitting ac 9 touch attack can fail at these levels though, probably around 25% of the time)[/quote]
Ray of enfeeblement is a very useful spell but, somehow, all of your assumed scenarios seem to be dramatically in the player's favor.
Yes, if the ray of enfeeblement hits (if the hydra is not in melee, this will be about 80% of the time; if the hydra is in melee, it's only 40-60% likely to hit), it will dop his damage and attacks by -3 fully 50% of the time. That could well decide the fight though it's likely to still hit enough in the LONG time it takes to kill something with fast healing 15 that some serious healing will be needed after the battle. That doesn't mean that it's going to work out that way on a regular basis though.
Hence my example though, if a single melee brute can hold his own, and even has a chance of winning, at level four but would not at level 3, and should have a much easier time at level 5 then CR 4 doesnt sound too bad. The party I listed above used some very basic tactics and almost couldnt help but win.
You're overly optimistic here. The party who used those tactics you listed has a good chance of winning but could still lose quite easily. If they ever fail to deal 15 points of damage per round, the hydra heals up and it's harder for them the next round. The hydra just needs to live long enough to hurt them. Even if it only hits once per round, it will wear them down if it lives long enough.
In any event, the challenge seems significant enough that it is likely to consume resources similar to an EL 6 or 7 encounter which means its CR is off by several points. (Or that it simply doesn't fit the CR system well--CR 4 is a more valid estimate of its challenge to 6th and 8th level parties).
