Yeah - That wizard is tough, but there is nothing you can
do vs good prep. I don't know who this Hedrack guy is, but
if he is a high level cleric, he can probably do well given a
use of the ol' spell resistance.
The problem as I see it, is that you don't want to construct
encounters specifically for the wizard. That is unfair to the
rest of the group.
I think the problem lies in the ability to teleport to town
at whim, no "out-of-dungeon" encounters (assassins),
and easy access to purchased magic. It becomes
somewhat of a video game.
Even with teleport taken away, high level parties generally
have ways to rest (rope trick) that can keep them protected
but this evens out as they will actually use up their items,
healing, spells, etc. without re-stocking. The trick will be
keeping the party alive to make the game fun - at that point
the few super fireballs (or other high damage spells with
high mortality) become precious.
If you are stuck in an evil place, how many times will you
want to rest? Rope tricks can be found (with detect magic)
and dispelled. This happens a few times and the party will
get very conservative.
Apart from that strategy, a few good tactics can make any
spellcaster have a bad day:
Ready Actions - If used properly, a spell caster will have a
hard time getting off his spells - Make sure you ready area
effects tho (shield + 20dex + mage armor = high AC vs even
touch attacks). Also, take a look at the rules for mind affecting
spells vs. concentration (the DC of the spell + you spell level so
for a high level cleric (24Wis) with spell focus = DC19+2 (say
a hold) + 5 (his cone of cold) = DC26. His max'ed concentration
is 14 + 2CON = 16; Still a 50% of a ruined spell. And that is
if he makes his will save (DC21) vs the hold.
I assume the wizard is flying around - a targeted greater
dispel works wonders (tho he will still float nicely to the floor).
If you really want to be mean, I agree with the others,
have a nasty flying elemental (with a high BAB) grapple
him when he moves away from the party. It could probably
pin him without a problem and drag him off someplace
unhappy. I doubt he is carrying a weapon to threaten
anyone with an AOO.
I wouldn't stress about this too much; Things tend to
even out in the long run.
~D