According to most here (based on past posts) Diablo is a pushover.  For
me Diablo always seems like a PITA!!!  You need mucho fire resistance
not lightning.  You didn't say what kind of Druid other than that you
have the wolves etc.  What is your main attack?  Sometimes joining a
group is the only way.

75 LR and FR if you can manage it.  Now's the time to stick some
diamonds in a 3-hole shield if you have any.  Armor class is useless
against him, as are your minions.  Don't even bother resing your merc,
but do go in with OS up.

Remember, all Act bosses do 10x damage against all minions.  His
"breath" is the LBOD, or Lightning Blast of Death.

No need.  You could still have killed him.  He can't heal as long as
you don't leave him alone too long, so it's just a question of
patience, though it can be a long fight.  Without CB or Static, count
on 10-20 minutes, minimum.  A few important tactical points:

1. Try to stay out of his face; being behind him or at least well to
the side will protect you against most of his attacks.

2. Learn to recognize his "inhale" animation, which precedes the LBOD.

3. If he sends Firestorm at you, just run out of it.

4. If he starts the LBOD at you, DON'T run away.  I know that is your
first impulse, but it will not save you.  Instead, run to the side,
around him, and out of the blast.  FRW boots will help a lot with
that.

But really, unless you are playing HC, what's to be afraid of?  All he
can do is kill you, and in SC you can just say, "Not even MY death
will save you from ME, dog-face."  The principal danger in HC is that
he will bone cage and fry you with the LBOD.  There is no way out of
that but Alt F4.

Better, but will still need frequent recasting.  The major benefit is
that the Griz can keep Diablo busy and in place where your elemental
attacks can hurt him.  Fissure is better for this fight than Volcano,
IMO.  I once soloed Diablo with a level 25 druid using an unsynergized
level 2 Fissure from a pelt I found.  In HC, of course.  Took half an
hour, but I was not in trouble at any point.

Oh, please.  Open Bnet is a sewer of cheating, and if you are going to
chicken out of soloing Diablo, why play at all?

An unworthy goal, IMO.  You should want to KILL HIS REPTILIAN @$$
YOURSELF.  He's really not that hard to kill... just a lot harder than
any other monster you have encountered.  And if you die, go right back
at him (leave a tp up in the CS).  He's already done his worst, what
more can happen?

-- Roy L

First rule: forget about your mercs, they are going to die. Don't
waste money reviving them.

Second rule: immediately after triggering the Big Red Dog, run away
and open a town portal far enough back from the pentagram that he
won't follow you there.

Third rule: go back to town and pick up all the charms you've been
saving for a rainy day, and put them in your pack to max your
offensive and defensive power.

Fourth rule: when you portal back to Diablo's crib, *immediately*
open another portal. Do this every time you retreat to town for more
mana and life pots.

Fifth rule: if possible, use a range weapon against Diablo. Stay
away from his talons. The further away you keep yourself, the longer
you will live.

Sixth rule: when he vomits forth his red lightning blast, run to the
*side* -- do not try to get out of range of it. The blast will
follow you around, but  you can out-run it by going in a circle
around him.

Seventh rule: hit and run, hit and run, hit and run. Don't try to do
much damage at any one attack, because you won't be able to. Just be
content to chip away at his life bar.

Eighth rule: when you get low on potions, break off your attack and
get your a.s back to town for more. Never let your life ball fall
much below half-way during your fight, and never let yourself run
out of life potions while still going toe to toe with him.

Ninth rule: keep moving to try to avoid his bone cages. Bone cages
can kill you if you do not have a powerful weapon, such as a
hard-hitting maul, to break out of them. Once the Big Dog has you in
a cage, it only takes a second or two of his lightning attack
playing over your body to kill you.

Tenth rule: when you finally kill him, do a little dance on his
corpse. You've earned it.

-Al-

Get a ranged weapon.  The grizzly will be constantly recasted as he dies
as a distraction.  You will need all your mana for that, so having a
no-cost ranged attack is a must.

Normal Diablo does NOT regenerate life when you go back to town, so do
not be afraid to go back as many times as needed.

For potions, you should farm up as many chipped gems as possible to make
a full belt of rejuvs (3 life potion + 3 mana potion + 1 chipped gem = 1
rejuv, 3 rejuvs = 1 full rejuv)

Farm the vendors in A4 by leaving and re-entering the zone until you
find some more fire/lightning res gear.