I figured I'd better make a guide for this, because I've seen so many people having trouble defeating him, and I defeated him in one run. Not boasting, it's the truth. 'shrugs'

First to find him he's on the far West of Astryl's Tranquility

I've split this guide into three parts. Level and Proficiency, Equipment, and the Battle itself. So, lets get started.

1. Level and Proficiency
(Fun Fact: I had to type proficiency a million times before I got it right :P)

First, defeating Vorpar is hard enough already. You want to get onto the highest level possible. Well, although the highest level currently is 70, level 60 is enough. Besides, leveling up is hard! You want to defeat him as fast as you can but not get defeated on the way.

Second, proficiencies:

Wind

Wind works fairly well against Vorpar, as it deals high damage and takes enemies down quickly. Plus it only focuses on one opponent. You'll see what I mean later on.

Earth

Earth is possibly one of the worst elements. It protects itself and heals itself. Sometimes. But it may be a good idea to use it as a front tank, but in this battle, tanks usually get taken down easily

Fire

Fire does work well, but only for one part of the battle, because it deals multi target damage. The thing is, you usually only have one enemy, so, well, not very useful

Water

Water is pretty much the same thing as Earth, except that it doesn't heal itself but protects other pets. Its second 'attack', though, doesn't even deal damage!

Light

Light is a pretty good element, since it heals al your party pets from the amount of damage dealt. Possibly. Unfortunately, it is not very good at healing itself.

Shadow

Shadow is probably the best element. You would want to have a Shadow pet as your first party pet, since it deals a good amount of damage while healing itself as well. Plus, it has a chance to cause Siphoned, which also deals damage for three turns and heals whoever had cast it.

There are a lot of combinations to choose from, but here are the most popular ones
Shadow, Light, and Wind. The balanced party
Shadow the first one because I explained it before, Light the second so that it can heal itself and the Wind pet, and Wind the last since it can't heal itself and the third slot is usually the least aimed at, and it deals good damage.
Light, Fire/Wind, and Fire/Wind. The offensive party
In this case you would want to switch one or both Fires into Wind. This build takes enemies down quick, but unfortunately cannot heal itself very well and may get taken down quickly by Vorpar. Light can heal the party but not quickly enough since there is only a 50% chance that it will heal and it won't heal very much either, unless it lands a critical, and gets that 50% chance. Fires switch into Wind because most of the time you are only battling one opponent, but Fire is still pretty good during Vorpar's Plane Shift. Switching just one pet into Wind would be fine, but be sure to stock up on exlirs.
Earth, Water, and Light. The defensive party
The build is not very effective against Vorpar as it is mandatory for you to take enemies down quickly. Even though the Earth, Water, and Light combination makes an almost invincible build, it is very slow in attacking and you would be spending, i dunno, half an hour trying to defeat him.

But, its your choice on whatever works for you.

And yes! The proficiency points. I put 2 on health since you need to survive (obviously) and 1 on whatever stats thats needed (You can see the recommended stats below the place where you add proficiency points), because it extends your stats and gets you to battle better.

But you can see what you get when you add to some stats. You would need like all of these.

Strength: increases physical damage and physical mitigation
Intelligence: increases magical damage and magical mitigation
Dexterity: increases critical hit, accuracy, and quickness
Agility: increases physical/magical mitigation, avoidance, and quickness

Physical Damage: determines damage dealt by physical attacks
Magical Damage: determines damage dealt by magical attacks
Physical Mitigation: reduces damage received by physical attacks
Magical Mitigation: reduces damage received by magical attacks
Critical Hit: chance of dealing 100% more damage
Accuracy: reduces chance of enemy avoiding attack
Avoidance: chance of avoiding enemy attack
Quickness: determines order of actions each turn

2. Equipment
Now, you first-timers have a slightly bigger chance of winning. Why? Because of the new equipment released from the Lost Grove. Old players didn't have those awesome equipment, and therefore had to save up money to buy Mythicals on the Trade Broker, or run the Dungeon of Forsaken a couple times just to get that kind of equipment. But, now, there are a bunch of equipment from the Lost Grove piling up in the Trade Broker, usually from 2k - 15k. Pretty cheap, huh? Those may look like weak rares, but they're even better than Mythicals. One small note, is that it can only be equipped on level 60 pets, but I think that's dealt with already. To search for it, just type up 'exotic' on the Trade Broker in Relics, Armor, and/or Accessories.

Of course, It is very important to match up equipment to the elevated stats from your proficiencies. From the Lost Grove equipment, its easy to see, or you can just tell by the color, but I'll tell you here.

Storm Caller = Wind
Warden = Earth
Pyromancer = Fire
Tidal Lord = Water
Lightbringer = Light
Reaver = Shadow

See what I mean? Easy.

But, if you even can't get those, look up possible equipment from my friend Snowcrystal's Equipment Guide here. Remember, add to stats.

3. Battle
And yes! The battle itself. Well, if you're looking at this before you go to fight Vorpar and you have the Elemental Tether, sorry, it's not gonna work. Its just gonna make Vorpar angry.
A-n-d, I got this genetic test pic from Amarok's Walkthrough of Sylestia:


Simplified explanation of the fight:
He will first use Choking Mists on all your pets for three turns, which deals damage and decreases pretty much everything (Damage, Mitigation, Critical Hit Chance, Avoidance, Quickness) by 20%. Not much of a big deal, really. But, when the Tsunami Icon appears on him, order all your pets to block. It's important to focus on this fight, or else you'll miss something and pay a heavy price.

Some time in the fight, he will use Planar Shift and summon two Elemental Minions. What he did is that he moved into another plane, so you can't hit him at all. Your goal here now is to kill the two Elemental Minions as fast as possible, because each turn he will heal himself from his minions. If you manage to kill both of them within 15 turns, which is how long Planar Shift lasts, he won't gain as much health. If you don't, there's a big chance that you're gonna die.

In this fight, make sure you stock up on exlirs and draughts, in case one of your pets die. One simple trick that a lot of people I've seen use is go the Aryth's Spire and drink a few potions before battling.

Good luck!