Victim said:
Yes.
Victim said:
The DR granted by Stoneskin excels in situations where the main threat is coming from lots of low damage (non adamantine) physical attacks. Otherwise, it's not so great. For instance, if people can reach the target, then alternative attacks besides damage can be used - like grapple or trip to restrict the target's actions and set up Power Attack for breaching the DR. If average attacks are doing about twenty points of damage, then Stoneskin is preventing about 1/2 damage. Like Displacement, but higher level, a bit narrower (displacement can help against touch attacks and the like), and longer lasting.
Without a component cost, the spell could use a hit in duration - I think that the upfront cost counterbalances the tendency to use 10 minute spells as just in case prebuffs - but it hardly becomes the uber 4th level spell. Greater Invis (while it lasts) is similarly good on defense - 50% miss chance plus certain misses from attacks aimed in the wrong square - denies dex to most foes, and can be used to get surprise.
The first difference is that Greater Invisibility is one round per level. Stoneskin lasts 100 times as long. This often means 2 or 3 (or sometimes even 4+) combats for one spell (depending on how often the protected creature gets hit), not one combat. Multi-battle protection is pretty nice. One would have to cast Greater Invisibility several times to get the same protection.
The second difference is that Greater Invisibility is more obviously a spell (unless the protected creature does nothing). Any opposing spell caster will more likely cast a spell to counter the Invisibility in some way before casting a spell to prevent DR/10 that the opposing spell caster is probably not even aware of (unless table talk is allowed to affect the game).
DR / 10 can also sometimes totally prevent poison or other damage, even if the protected creature gets hit if the attack does 10 or less damage (which many special attacks do).
At 7th level when Stoneskin first shows up, PC fighter types (unless using some of the newer books or unless a Half-Orc with 18 Str) might be doing 6 for Str with a two handed weapon, 7 for the weapon, 2 for Weapon Specialization, and 2 for magic. That's 17 on average (for a fairly high end PC two handed weapon fighting Fighter) without additional magic, 13 on average for a sword and board fighter.
NPC fighter types should typically average somewhat less than PC fighter types. Maybe 14 two handed weapon, 10 sword and board points of damage. So at 7th level, it stops about 70% to 100% of the damage of NPC fighter type attacks compared to the 50+% (depending on if the opponent knows where the target is) of Greater Invisibility. If the NPC fighter type Power Attacks to get through the DR better, he hits less often which again, protects the PC with the Stoneskin even more.
Ditto for other CR 7 monsters out of the Monster Manual. Almost all of them average way less than 20 hits per successful attack that you mentioned. The average and max damage for them (without criticals) is:
Code:
11.5 14 Aboleth
19 26 Animated Object Gargantuan
11 16 Black pudding
17 24 Bulette
26 44 Cachalot whale
4 5 Chaos beast
11 14 Chimera
12 17 Chuul
13 18 Criosphinx
15 18 Dire bear
11 16 Dragonne
5.5 8 Drider
21 28 Elasmosaurus
13 20 Elemental, Huge air
20 29 Elemental, Huge earth
13 20 Elemental, Huge fire
6.5 9 Elemental, Huge water
24 31 Elephant
9 12 Formian, taskmaster
8.5 13 Ghost, 5th level fighter
19 26 Giant, hill
14 21 Golem, flesh
10.5 14 Hellcat (devil)
9.5 14 Hydra, eight-headed
8.5 13 Hydra, six-headed cryo-
8.5 13 Hydra, six-headed pyro-
11 16 Invisible stalker
9.5 13 Lillend
3.5 6 Medusa
10.5 14 Monstrous scorpion, Huge
11 16 Naga, water
2.5 4 Nymph
22 29 Ogre barbarian
21 28 Remorhaz
32 42 Skeleton, cloud giant
14 21 Slaad, red
4.5 8 Spectre
4.5 7 Succubus (demon)
14 14 Umber hulk
17 20 Vampire, 5th-level human fighter
11 16 Yuan-ti abomination
Even if one drops the non-combatant Drider, Nymph, and Succubus out of this list (the rest of these creatures will attack in melee as an alternative), the average damage is 13.7 and the average max damage is 18.9.
A 7th level Fighter with 64 hit points and a 7th level Stoneskin up can typically handle 13 such 13.7 successful hits before going unconscious. The same Fighter with Greater Invisibility (assuming his square is known) can handle 10. The same Fighter with no special protection can handle 5.
Per casting, Stoneskin will typically stop a lot more physical damage than Greater Invisibility. It will not stop things like single target spells.
From a healing point of view at 7th level, stopping 70 points of damage is the equivalent of 2 4th level Cure Critical spells and a 3rd level Cure Serious spell (or 7+ 1st level Cure Light Wounds spells). That's quite a savings for the PC healer. That's at least 3 rounds of healing that can be often handled before any combat even starts.
At 15th level, it's one 6th level Heal or 4 4th level Cure Critical spells and a 2nd level Cure Moderate spell.
So yes, it is worth more than most other 4th level spells with regard to physical combat protection (or healing afterwards).
Greater Invisibility is worth more against spells (no argument there), but still typically has to be cast once per combat.