Has anybody ever actually created one? Aside from the obvious debuff of being a Tier 3 character (not even as good as Tier 2 Rogue, Bard, and Gadgeteer).

My thinking is that: He would be Male (for variety, as I always make my Bards and Gadgeteers Female for the stamina regeneration items). He would be Human, to give him a good early stat spread (45 to all stats to start, no resistance penalties).

Stat-wise, I'm going for Dexterity and Speed first (early Reflextion and SnakeSpeed allows him to hold his flank, with a shield, as well as to act quickly to protect, heal, and cure the party as needed). After that are the "fighting stats" (Strength, Vitality, and Senses). This particular Priest is ignoring Intelligence and Piety (though I did put enough points into Intelligence so that, after the Trynton Fountain, Intelligence and Piety will be equal (60)).

This build would finish, so that Strength, Vitality, Dexterity, Speed, and Senses would be maxed, at level 40 (41 assuming that Intelligence and Piety are evened out).

Obviously, all 37 spells would be picked, rounding out his spellbook.

All relevant skills would be maxed, going for Mace and Flail and Shield skills (either Mauler or Diamond Eyes, whichever gives me more average damage).

First play, I had a male STR/INT priest. I was tired of him not getting extra attack; that combine with the lack of Dual Wield skill led me to change him into a lord later.

Yes, this meant that, for a while, I had a character who was not able to develop spellcasting (still had his old spells, but couldn't learn any more or raise his skills), but did have Power Cast (which you don't usually get on non-casters) and could even develop it by casting spells. Worth noting that The Mauler has one interesting advantage: It can be used as an item to cast Crush. Normally, this might not be too important, but seeing as the Priest lacks long range direct damage (until level 18+, and even then it feels inefficient to use it when you only need to hit one foe), this could actually come in handy.

I like Dwarf for this build because:
* STR and PIE are already high from race, meaning you get more bonus p0oints. Also, you can get Power Strike sooner than a character who starts as a Lord or Valkyire. (Drawback is being slow to get extra attacks, but the extra stat points you get could be used to address that.)
* Damage reduction. This makes the Priest's low-ish HP less of a drawback (though, in my experience, it doesn't usually matter; would matter for a front line Bishoo, however).

In this MDP, the Priest has somewhat favorable HPs (for a caster). The HP hierarchy goes as follows: Bard>Gadgeteer>Priest>Alchemist>Psionic>Mage.

None of these six characters have the raw melee damage to justify dual-wielding (the Bard and Gadgeteer have the Dual Weapons skill, while the casters lack it). Therefore, weapon and shield for the non-glass cannons.

Stat-wise, you want your "tougher characters" (Bard and Gadgeteer here), to max Strength and Dexterity first. The Priest, as a variant, will max Dexterity and Speed first, for early Reflextion and SnakeSpeed. The "glass cannons" will max Intelligence and Speed first, going for PowerCast and SnakeSpeed early.

For spells, all four casters will completely fill out their single spellbooks by level 35 at the latest (assuming that they found or bought no spellbooks). Of course, this is ridiculous, as they should have rounded out their spellbooks by level 30 or so, by the time that they visited Arnika (pick wisely).

For skills:

Melee: The Bard and Gadgeteer should max Close Combat, Sword, and Shield skills. The Battle-Priest should max Close Combat, Mace and Flail, and Shield skills. The other casters should max Close Combat and Staff and Wand skills.

Ranged: The Bard and Gadgeteer should have Tripleshot Crossbows, and should max Ranged Combat and Bow skills. The casters have no choice, and should max Ranged Combat and Throwing and Sling skills.

Magic: The Bard should max Music. The Gadgeteer should max Engineering. The Priest should max Divinity, and all six realm skills (no PowerCast). The other 3 casters should max their single spellbook skill, as well as all realm skills.

By level 30, you would be expected to have already beaten the game; typical levels for clearing the game are mid-20s for new players or early 20s for experienced players.

Arnika is generally expected to be reached around level 6 or so (unless the player goes to the UBC first and does multiple quests before heading to Arnika, of course). Priest only really cares about maxing Earth, Divine, and maybe Fire,
* Water has a bunch of low to mid level spells that are useful, but none past 4th level.
* Air has Cure Poison and Purify Air, but nothing higher.
* Mental is good for Sane Mind, but that's only 5th level, and there aren't any higher level priest spells of this realm. Even then, if your party also has a Psionic, the Psionic is better able to use Sane Mind due to being immune to the effects it cures; a Priest might very well be too insane to cast that spell when you really need it.

Assuming that you reached Arnika early, you would have to deal with the Arnika Road nasties.

If reaching Arnika at level 21+, you would destroy all enemies in your way, as well as have a new experience grinder (level 21 Savant Slashers).

This would allow for you to create your "dream party", a MDP with 5 stats maxed by endgame. I'm going for quality here.

Wait, entering Arnika on level 21?
Are we talking about that Arnika, with the bank, HHL, airport (spaceport) and savant tower?
That Arnika that is meant for early access, basically the first go-to spot right after leaving Monastery?

Why would one deliberately avoid it, and enter it first after level 21?

Also, enemies scale with hero average party level. So when you enter Arnika on level 6, you encounter only weak savant drones and also weak thieves (different kinds), around level 10, these get replaced with stronger thieves (having 70~120 HP and a lot deadlier attacks), and around level 13 the savant drones get replaced with huge uglies (who also have various levels of strength, and some really are meant for strong parties, yet again, you won't see them when your party is low-level, even when playing on HARD)

As for dream party, it are not the stats that make a party 'dream' like.
While every class has its' own strengths, eventually, especially at the end of the game (or in the sea, which is also more to the end, than the middle, story wise) you will find many classes lacking.

Especially mind-altering attacks become a nuisance, when your Samurai will start killing your mages and other low-HP friends, before you manage to cast Clear Mind (or what is the spell to remove mind altering statuses)

Or master of archery (like Ranger), will fail to hit long-distanced enemies, despite his stats, skills and items are top-notch, and when he manages to hit, even with ammunition like peacemaker, won't guarantee an actually better outcome, not to mention, that archery needs clear line of sight, unlike spells, that can hit either en mass, or ignore objects (friend or foe) in the trajectory (compared to mind stab, that might have only thrown range, but you can aim at any enemy, even if there are active objects in the path)

Honestly, dream party would be one Bishop and 5 Psionics.
Locks & Traps would be handled by Poseur's cap + Thief Buckler + Knock Knock / Divine Trap
Bishop can become a solid tank, especially with Guardian Angel
Even magic-resistant/immune enemies, even if not succumbing to paralyze or web, can be subdued, if the battle can be dragged long enough (which is possible with boosting priest and healing him)
While Bishop lacks in all aspects, compared to any other class, and is possibly the weakest tank possible (if we ignore faerie mage), also is not the ideal thief, he can eventually fill those positions with success, letting your party run through Dominus)

Early: Mind Stab can do the trick for 99% of encounters
half MID: Psionic Fire can handle even strong enemies, after mastering walk+wait, even Juggernauts
MID: now it will become tricky, as bishop nor psionics can handle magic resistant enemies well, due lack of good items and also low HP, so Battering Hoggar, who would resist nearly every Paralyze or Web (unlike Hoggar, who can succumb to paralyze nearly instantly) should be avoided. But XP can be farmed from most of enemies, again, with Psionic Fire, and should the combat drag for too long, Ego Whip can step in (despite not offering full level 7 casting power)
half END: now you should already have Psionic Blast, and clearing most enemies would be in worst case just a question of reload and retry (considering you didn't tick Iron Man), but the spell is not only devastating, but extremely helpful, as it can hit even enemies, you do not see (in areas, like Rapax Castle, where even Fireball cannot guarantee a certain hit of your enemies, Psionic Blast can hit even enemies, that are far away, either running away or just trying to approach you from absurd angles of the castle labyrinth hallway web of a castle)
You can now even face enemies under water, again, Psionic Blast proving as universally useful, and having 5 casters who mastered it, makes your party "2-rounds winners" for most of the cases. And you don't even need to use the complex move+wait tricks from before (to force enemies position right in front of you, so all/most can be hit by psionic fire / ego whip)
END: now comes the true purpose of having 5 psionics into light: needlessly too many enemies can now control your party (turncoat, insanity...) but 5 out of 6 of your party members simply do not give a single nick nolte. While they waste their best spells on you, in worst case scenario your bishop turns against you, but he won't truly change much, even when he starts flailing around with his mace or staff... (which can be removed before combat, when such situation is anticipated, barehanded - he is harmless just as a kitten)
There will be enemies, like golems and such, with absurd high magic resistance, but you would already have high-end weapons and armor, that even Psionic can equip, plus all the buffing spells, that will help you survive long enough in order to win. With no or little loses on your side.
Hint: select dwarf for psionics as a race, due the natural damage resistance, which will greatly improve your success ratio just during melee combats (which often cannot be avoided)

Within range. I believe that, if you enter Arnika at a really low level, like below 5, you may encounter those level 20+ enemies that you have absolutely no chance against at that low a level. (Note that this is only going to happen if you deliberately hold off leveling.)

If you enter Arnika at level 21 (this is a breakpoint for treasure chests with a level sensor):

You will be able to clear the Arnika Road that used to give you trouble, and can cast level 6 and below spells at power level 7 safely.

Level 7 spells will be able to be cast at power level 4 safely.

You will be able to handle level 21 Savant Slashers and level 22 Savant Minion that WILL spawn at your level (you better have some ranged combat gear to deal with the latter's magic resistance).

what I perceive as most motivating : on higher levels, map generates better loot.

So, would I enter Arnika on level 20+, would I possibly get loot like this (excellent bow from random drop in rappie castle)

https://imgur.com/nQWbJTO

I am on level 21, btw.

Great, finally, a GOG member agrees with me.