Are there limits to object Sizes when a character uses Metamorphosis?

Question

I intend to use an NPC to make her attack a vessel. The NPC is capable of using Metamorphosis as a multiclass Ardent 7, manifester level 11. My idea was to make her metamorph into a flying creature, fly directly above the vessel and then turn into a huge rock, crushing the deck and part of the hull.

The vessel in question is a Dromond, I use "Stormwrack", for sinking the vessel 15 hull sections (each a 10 feet cube) would have to be crushed, each with hardness 5 and 80 hp. The Dromond has a 20 feet by 100 feet space. The whole ship has AC -3, attacking a hull section is AC 2.

My problem is to assess the power of my imagined kind of attack. Metamorphosis says:

You can also use this power to assume the form of an inanimate object. You gain the object’s hardness and retain your own hit points. You can take the shape of almost any simple object you can think of, such as a chair, a sword, or a rug. (...) You cannot use this power to assume the form of a psionic item or a magic item, or any object with a hardness of 15 or higher. (...)As an inanimate object, you lose all mobility. You retain your normal senses and your abi lity to speak. You can manifest a power if you make a Concentration check (DC 20 + power level); however, doing so ends the duration of this power. If you take damage while in the form of an object,your actual body also takes damage (but the object’s hardness, if any, protects you). Expanded Psionics Handbook, p. 117

Stone does have hardness 8, so turning into a rock is possible. The NPC would take falling damage minus 8 points of hardness. But how much damage would the ship take? The NPC could turn into a 11 HD creature - but there seems to be no limit regarding objects.

I see the following possibility to limit the Size of objects you can turn into using Metamorphosis: The power specifies that the manifester retains her hp. An inch of stone in a 5x5 feet square has 15 hp. (PHB, p.166) The character has 117 hp. So you could say she could turn into a stone slab of 5 feet by 5 feet 7 inches thick. This slab would have 105 hp. You could transform it into a stone ball of roughly 3 feet diameter. This is a massive boulder - but just how massive in terms of damage?

A granite ball of 3 feet diameter would weigh roughly 1,16 tons. This is more than 11 times 200 lb, so the DMG section for falling objects applies: This boulder causes 11d6 points of damage on a 10 foot fall, for a 100 feet fall 20 d6 damage would be applied to the ship and 9d6 of damage to the NPC (minus 8 pts of hardness).

While this seems reasonable, I am still wondering: Are any of the figures given above limits inherent to the power or could you just use Metamorphosis to say "I turn into a mountain" and bury the ship? Or simply put: How big a rock can this character turn into using Metamorphosis?

Answer 1

Technically, there is no size limit listed for object forms taken via Metamorphosis.

As a reminder, here are the various results of Metamorphosis compared (credit to the folks on MinMaxForums for compiling this info):

Properties	Metamorphosis	Metamorphosis Obj.	Gr. Metamorphosis
Note		Inanimate object	as metamorphasis, except as noted.
Type(s)	self; no con, ele, out, und, inc, ecto, gas, templates	gain hd, retain hp	unique, incl incorp, ecto, gas.
HD limit	ML or 15hd	—	max ML or 25hd
Size limit	no smaller than fine	none, but hd < 15	fine to colossal
Ability scores	change s/d/c	—	change s/d/c
HP/BAB/Saves	base = no, f/r change from stat, hp=yes	retain hp	base=no, f/r change from stat, hp = yes
Original Su and SLAs	retain all, but body part requiring	—	class = yes, form = no
Original cast / manifest	manifest	manifest with concen dc=20+pl	manifest
Healing	hp as nightly rest, no ability heal	—	hp as nightly rest, no ability heal
Slain	reverts	—	reverts
Other	lose original template abilities	simple object, complex = skill check	change 1/r swift action
Focus / component	none	none	xp = 200
Gains
Movement	mundane move, max 120' fly, 60' non-fly	lose mobility	mundane move, max 120' fly, 60' non-fly
Natural Armor	yes	—	yes
Natural Weapons	yes	—	yes
Racial skill bonuses	yes (+10 disguise)	—	yes (+10 disguise)
Racial feats	yes	—	yes
EX	attacks only	—	yes
SU and SLAs	no	—	all Su, no SLAs
Equipment	melds if cannot be worn	—	melds if cannon be worn

As you can see, the only limit related to size when taking an object form via Metamorphosis is the 15HD limit.

Generally speaking when changing into a creature, one can use either the base weight of the character recalculated by the size change, or the generic listed weight of the creature, if such is given in the creature information.

Only, an object does not have HD (unless it is animated). Unless one construes the HP per Inch metric of objects to be the equivalent of HD, the lack of HD creates an impass. Furthermore, different materials have radically different densities, and thus different effective weights for the same size of object.

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As a suggested resolution:

• Select a creature with a listed weight agreeable to the DM at the maximum HD limit of the power.
• Use that weight as the baseline measuring stick for the maximum amount of material one can metamorph into.
• Alternatively use the HP of the source character compared to the HP of the target material to establish a baseline.
• Perform size/weight calculations for the DM approved baseline comparison as tolerable for your desired level of realism.
• Being that your character likely does not possess the Exotic Weapon Proficiency: Falling Like a Rock feat... applying the Improvised Weapon rules seems appropriate.
• If the attack is successful, reference the Complete Warrior (p.159) for the text on damage from extra heavy improvised weapons (the table does not reflect all of the rules text), and or possibly use the falling damage rules as the DM feels appropriate.

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For reference, here are the statistics for all of the possible options for changing form in D&D: Shapeshifting Comparison in D&D