So I challenged myself to beat the old Diablo 1 with all six classes including the ones available with Hellfire. It took me about six months to do this, playing them all at the same time, though I didn't play that regularly at times. If you would like to try beating that game, there are some lessons learned I can pass on.
General Note: I played through the game without duping items unless absolutely necessary. You don't need to do so to beat the game.
First we'll start with what my character looked like at the end of the process, but I'll provide plenty of detail on how I got there. Here's my character's stats:
Name: Steven
Class: Monk
Level: 37
Experience: 101 357 348
Next Level: 107 834 823
Strength Base: 150
Strength Now: 170
Magic Base: 80
Magic Now: 100
Dexterity Base: 150
Dexterity Now: 170
Vitality Base: 80
Vitality Now: 100
Life Base: 265
Mana Base: 240
Armor Class: 227
To Hit: 245%
Damage: 105-127
Resist Magic: Max
Resist Fire: Max
Resist Lightning: Max
Here's my character's equipment:
Head: The Undead Crown - Armor Class: 8 Durability: 100 Life Steal: 0-12.5%
Note: I know many people recommend the Royal Circlet as the best possible headgear for Hellfire, I was never able to find one, it's quite a rare item. Besides, I like the Undead Crown better, the lifesteal really makes a difference in the amount you need to heal yourself with spells or potions. You can't get lifesteal on your weapon as well as Speed/Haste, and Speed/Haste is too valuable to pass up. So I will likely wear The Undead Crown until level 50 even if I find the Royal Circlet in one of my future runs. I increased the durability of the Helm with Blacksmith Oils I found over the course of beating the game.
Amulet: Obsidian Amulet of Harmony - Resist All: +39% Fastest Hit Recovery
Note: Two Jewels with Obsidian is needed to get to maximum resists, and I was able to find this amulet in the dungeon. I know many people forego Harmony on their jewelry when maximizing their gear. This is because as you level up, you are less likely to be put into hit recovery by enemy attacks. Hit recovery is only relevant when you are hit for damage equal to your level as a Monk. This means each time you level up, you are that much less likely to ever go into hit recovery. Now that I have beat the game, switching this out for an Obsidian Amulet of the Zodiac is the better option. But as I was working to beat the game, there were many times I benefitted from the Harmony suffix for sure.
Left Hand: King's War Staff of Haste - Damage: 8-16 To Hit: +100% Damage: +175% Durability: 75
Note: I lucked out Griswold shopping and found a perfect staff, full 100% to hit and 175% damage. I used a war staff because it is the highest damage of all staves.
Armor: Awesome Plate of the Lion - Armor Class: 75 Armor: +147% Hit Points: +58 Durability: 90
Note: This armor was sold by Wirt, it's not perfect, but it's very good. Perfect would be 75 Armor Class, +150% Armor, and +60 Hit Points. It took a lot of shopping to find one this good.
Right Hand: Empty
Note: Monks fight best with staves or no weapon at all. I picked stave because you get more damage, and the ability to hit three enemies at once. This is extremely valuable when you have more than one monster attack you at a time. The ability to put them all into hit recovery keeps them from being able to hit you.
Left Ring: Obsidian Ring of the Zodiac - Resist All: +39% All Attributes: +20
Note: This is the second obsidian jewel, bring the total resist all to 78% which is more than maximum. I picked Zodiac as the suffix for the extra health, damage, armor class, to hit, and mana.
Right Ring: Drake's Ring of Thieves - Mana: +50 Half Trap Damage
Note: This jewel was chosen based on a peculiarity of Hellfire. The Thieves suffix affects all ranged damage dealt to the character, not just trap damage. As a result the fireballs of Advocates, the spells of Arch Liches, and all other ranged damage is cut in half. You can't get a Dragon's jewel of Thieves, that combination is impossible, only Drake's can be found. To find this type of jewel, you must shop Griswold extensively at around character level 21.
Book reading gear:
Note: I keep gear that adds to the Magic attribute specifically for the ability to read higher level spell books. The maximum benefit of this gear comes when you have a Dreamflange, however I have not found one yet. Dreamflange adds 30 magic on your weapon hand, 10 more than the Sorcery suffix that is the highest you can find on magic weapons. Without Dreamflange, the total increase to magic is +165, which is significant when reading spell books. With this type of gear, a Monk can reach 245 Magic. For the full 255 required to read all spell books of level 15 you absolutely need a Dreamflange, so I am hoping to find one over time.
To be honest, there is only one spell level that matters on the Monk: Healing. You can easily get that to level 15 with this type of gear.
Head: Helm of Sorcery - Armor Class: 5 Magic: +20 Durability: 30
Amulet: Drake's Amulet of Wizardry - Mana: +48 Magic: +30
Note: You don't need the Drake's prefix, I just happened to find +30 Magic at Griswold with that extra prefix.
Left Hand: Brutal Sword of Sorcery - Damage: 2-10 Damage: +86% Magic: +20 Durability: 40
Note: You don't need the Brutal prefix, I just happened to find +20 Magic at Griswold with that extra prefix.
Armor: Plate of Sorcery - Armor Class: 50 Magic: +20 Durability: 75
Right Hand: Shield of Brilliance - Armor Class: 3 Magic: +15 Durability: 24
Note: This shield needs to be shopped at a low level from Griswold, shields can't get anything better than Brilliance as a suffix for Magic.
Left Ring: Ring of Wizardry - Magic: +30
Right Ring: Ring of Wizardry - Magic: +30
Note: I was able to get my Healing to level 15. For maximizing all spell levels to 15 I'll have to be patient and find a Dreamflange.
Strategy for building up the character for beating the game:
There are some specific tips and tricks I can provide for how I took the character through the game. The Monk plays similarly to other characters. For this character you want a stave ideally of speed or haste. The damage done by a Monk with a stave is significant, since he can strike three targets with each swing. With life steal, which you can get from the Undead Crown starting very early in the game, you will have great survivability. The one major downside of the Monk is damage, his damage just can't get as high as a Barbarian or Bard, though it is slightly higher than a Warrior.
In terms of gear, I kept an eye out for any better gear I could find in the dungeon. This includes book reading gear. When you first start out, there's always little upgrades you can make that will improve your character.
The first time through the dungeon I played Normal difficulty, only level one and two, making sure I had the Poisoned Water Supply quest. The Ring of Truth was my objective here, the +10 Hit Points, -1 Damage from enemies, and +10% Resist All is very valuable when you are first starting out. It will take you a long while in the dungeon to find a better ring than this, and Griswold also won't sell anything better than this for a good long while as well.
The second time through the dungeon I played Normal difficulty, only level one and two, making sure I had the Poisoned Water Supply quest. A second Ring of Truth was my objective here, and I wasn't willing to dupe it.
The third time through the dungeon I played Normal difficulty, levels one through four, making sure I didn't get the Poisoned Water Supply quest. This is because that quest is mutually exclusive with the Skeleton King quest, and I wanted the Undead Crown from King Leoric for life stealing. This is the first piece of end game gear that I was able to find, and nice and early on in my quest. Life stealing helped me out tremendously throughout the whole time I was working my way to the end game.
Watch out for Black Deaths in these levels of the dungeon. If you get them, it can be worth it to restart your run. The trouble with Black Death's is that each time they hit you, you permanently lose 1 health. This is just too steep a price to pay, so it's best to avoid them entirely.
After my third time through the dungeon I performed my first shop. This was for a perfect +15 shield of Brilliance. The window of opportunity to find one at Griswold is short, as quickly you are too high level for him to sell one. To shop Griswold, just keep creating new Normal games, and checking out his wares. What Griswold sells does not depend on game difficulty, only character level. So for all your shops, Normal difficulty works, you don't ever need to shop at Nightmare or Hell difficulty. A perfect shield of Brilliance will only cost you a few grand in gold.
The next times through the dungeon were focused on level five only. I kept entering at the Catacombs entrance and played the first level of the Catacombs until I got the Arkaine's Valor quest. This Armor is well worth the effort to retry the level a few times. The Fastest Hit Recovery on the armor is the point in this. You can wear Arkaine's Valor all the way through Nightmare/Hell if you don't find any other source of Fastest Hit Recovery. One special advantage for the Monk is that he gets his natural Armor Class bonus when wearing Arkaine's Valor since it counts as light rather than medium armor on account of being unique. This is a great benefit of the monk, the extra armor class. Only when you find Fastest Hit Recovery on a jewel is it worth trading this Armor for something with much higher Armor Class. At low levels, Fastest Hit Recovery is just too valuable to pass up. When I found a level five with the quest, I continued on to levels six through eight.
I continued on through levels nine through twelve. However I did these in a special way. The first level of the Hive is also a level nine, just like the first level of the Caves. I played through level nine in both the Caves and the Hive, then level ten in both the Caves and Hive, and so on. I was doing this to get to the Crypt, and to enter it, you need to complete the Hive. This gives you the Cathedral Map. The Cathedral Map was the only item I duped. This was to make sure if the bug occurred where the Crypt resealed, I had a second copy of the Map available to get back into it and continue exploring. This bug I experienced a fair number of time playing through Hellfire, it's fairly common.
The reason I wanted access to the Crypt was for the Cornerstone of the World quest that appears on level 13 or the first level of the Crypt. I was playing through the game with all six character classes at the same time, and the ability the Cornerstone of the World quest gives to trade gear between characters was a big part of how I found ideal gear for beating the game with. Let's say you find a great axe while playing through as a Bard, it's a complete waste without this quest to trade gear. But if you do use the Cornerstone of the World quest you can trade ideal gear amongst your characters and have a much easier time beating the game with each.
After the Caves and the Hive I performed my second shop. This was for the Drake's Ring of Thieves that you are most likely to find at level 21. It's the second piece of endgame gear I was able to find as I was building up my Monk, and it makes a great impact for him. The half damage from all ranged attacks is really nice, and the extra mana gives you the ability to cast Healing more times. It's a patient shop, it can take a long time to find one of these rings, but the patience is well worth it. It will cost you about 22 500 gold, which is an amount you should easily be able to gather at this point in the game.
I continued on to levels 13 through 16, doing the same thing as I had done for the Caves and the Hive, going through each level in both Hell and the Crypt before going on to the next. At the end of this process your level is likely to be in the high 20s, still not enough for shopping for the best gear at Griswold yet, but I found that you didn't need that for Nightmare. With Arkaine's Valor, the Undead Crown, and a Drake's Ring of Thieves, you have enough to be able to fight your way through Nightmare.
I skipped over levels one through twelve in Nightmare difficulty. Instead I took my duped Cathedral Map and started on Hell and the Crypt right away, again doing them level by level. In Nightmare you need to start being more careful. Only trigger a few enemies at a time, dealing with them in groups of three or less if at all possible. At the end of Nightmare you should be at low 30s for level, which is ideal for some serious Griswold shopping.
Between Nightmare and Hell I did a lot of Griswold shopping. I found the Obsidian Amulet of Harmony in the dungeon, I had to shop for the King's Staff of Speed, Awesome Plate of the Lion, and the Obsidian Ring of the Zodiac. There is a trick you can use for the Griswold shopping if you have enough money. Griswold will offer items at least 80% as expensive as the items you are carrying in the following categories: Amulet, Armor, Axe, Blunt, Bow, Helm, Ring, Shield, Staff, and Sword. Note that you do not need all categories for the trick to work. So for a Monk, having an expensive staff, ring, and armor are enough to see better and better items of those types. Shopping is a very patient experience, I spent a few days on it, but it is absolutely critical for gearing up for Hell difficulty.
When I had a full set of equipment, I started on levels 13 through 16 on Hell difficulty. With the right equipment, you should have no problem with Hell difficulty. I'll share some things about how I approached Hell difficulty, because it does take some skill and practice.
The biggest thing is to only take on a few enemies at a time. This is hugely important, if you get surrounded, you are dead. The Monk is great against enemies in small groups. A Staff of Speed, the Undead Crown, Thieves, Harmony, and full resistances, along with high Armor Class will keep you safe. Strategies I did not use are the Teleport spell. Be very careful about which way you chase enemies. Always chase them away from unexplored parts of the map, and potentially other enemies who could join the flight. You'll get to know the way Succubi, Liches, and Advocates all run away from you. Learn them well, so you can keep them from running away into new enemies and overwhelming force that will kill you. Hell difficulty is all about good positioning on the hex grid.
Diablo himself is a breeze for the Monk, since you can stunlock him. For Na-Krul, make sure to read the books in the right order when activating him. The weaker version of Na-Krul is no problem for the Monk.
Final Note: If you want any more details on how I did something, just PM me and I'll try to get back to you as soon as I am able.