Can a druid cast awaken on an already awakened tree?
Yes, although the effect of a second awaken spell doesn’t
stack. The tree would use the better result of the Intelligence,
Wisdom, and Charisma scores rolled by the two awaken spells.
Note that the caster can’t know the result of these rolls until
after the Will save required by the effect has been determined
(which means that the spell might unintentionally reduce the
tree’s mental faculties).
Are the additional languages an awakened tree or
animal gains based on the Intelligence of the caster or on
the new Intelligence score of the awakened creature?
The number of languages gained is based on the awakened
creature’s Intelligence score, although it can select only from
languages that the caster already knows. This might result in
the awakened creature being unable to fill all of its known
languages slots (if its Intelligence score is too high).
Can a druid (or other character) take an awakened tree
or animal as a cohort using the Leadership feat? If so, how
do I figure out how powerful the cohort is in terms of level?
To select an awakened creature as a cohort, the player must
work with the DM to set a level adjustment (LA) to add to the
awakened creature’s Hit Dice to find its effective character
level (ECL). Most animals have better-than-average ability
score modifiers, so level adjustments of 1 or higher should be
the norm. Compare the awakened creature to other creatures
with similar Hit Dice, attack modifiers, damage, and special
abilities to find starting values and work from there,
remembering that setting a level adjustment is as much art as
science.
Savage Species has more information on setting LAs for
unusual creatures.
If an awakened animal’s type permanently changes
back to animal (from magical beast), can it then become an
animal companion, familiar, or special mount?
Two very large obstacles stand in the way of this request.
First of all, there aren’t any simple methods of changing a
magical beast’s type to animal. By definition, an animal has an
Intelligence of 1 or 2, both of which are outside the range of
Intelligence scores granted by the awaken spell. Even
permanently reducing the awakened animal’s Intelligence score
to 2 or less doesn’t automatically change its type (note that
several magical beasts have Intelligence scores of 2 or less).
Second of all, unless the DM grants special permission, you
can use only “stock” versions of creatures animal companions,
familiars, or special mounts. A druid, for example, can’t
voluntarily take a 4-Hit Dice wolf as an animal companion, nor
could a wizard claim that the cat she’s using as a familiar was
the beneficiary of several wish spells from a previous owner
and therefore possesses ability scores beyond the norm. Even if
an awakened animal somehow qualified to become an animal
once again, it would have a higher Charisma score and more
Hit Dice than a typical animal of its kind, making it ineligible
for such use.
What are the Challenge Rating adjustment and level
adjustment for an awakened animal?
The rules don’t state such values, so it’s up to the DM to
decide. Chapter 4 of the Monster Manual suggests that an
animal should gain +1 to its Challenge Rating per 3 extra HD;
since awaken adds 2 HD along with an Intelligence and
Charisma boost, +1 seems like a reasonable value.
Since most animals don’t have a level adjustment listed,
calculating the effect of an awaken spell on LA is more
complicated. Your best bet is to look at the final result and
determine a level adjustment for that creature (rather than
calculating separate level adjustments for the original animal
and the awaken effect). Page 25 of Savage Species has advice
on setting level adjustments.
Does an awakened tree gain skills and feats?
Here we must determine which of two statements takes
precedence. The awaken spell states that the tree “has
characteristics as if it were an animated object” (except for its
type and its Intelligence, Wisdom, and Charisma scores), while
the Monster Manual indicates that any creature with an
Intelligence score has skills and feats.
The Sage believes that the spell’s description should take
precedence, so the tree wouldn’t gain any skills or feats.