Polymorph by caster lower than you

[SalterisSolaris]

What hitpoints will a level 8 Rogue have after using a Cloak of the Bat (http://www.d20srd.org/srd/magicItems/wondrousItems.htm#cloakoftheBat) to polymorph into a bat? The SRD notes that crafting the cloak requires a CL of 7, while the Rogue has 8 HD...

Normally I'd use the Polymorph-spell heuristic "retain your HP, only adjust by new CON". But in this case the polymorph line "The assumed form can’t have more Hit Dice than your caster level (or the subject’s HD, whichever is lower)" gets in the way... the resulting bat can have only a max of 7HD, right?

So... how would one calculate that?

[Doc_Maynot]

The cloak says it turns them into an ordinary bat, which has 10 Con. Just remove the Con bonus or negative from each level.
The hit dice part really doesn't matter since the cap of the is CL 7, but the form is one of a 1/4 HD creature.

[Duke of Urrel]

Don't worry. I agree with Doc_Maynot, and I would like to add that the following line, which appears in the description of the Alter Self spell, also applies to the Polymorph spell, and therefore also applies to the Cloak of the Bat.


Your class and level, hit points, alignment, base attack bonus, and base save bonuses all remain the same.

I believe this rule saves you from having to worry about the "whichever is lower" clause.

While you are polymorphed into a bat, you are still an eighth-level rogue. If your magic item could turn you into anything other than a bat, it could not polymorph you into a creature that normally has more than seven Hit Dice, such as a hill giant. As it happens (and as Doc_Maynot has pointed out), the item changes you into a bat, which is a creature that normally has only 1/4 of a Hit Die.