You should not proceed with the campaign if you already have a character that has completed the story arc before you have gotten to that point in the campaign.
When you have completed the campaign, skipped it entirely on a secondary character, or if you ever need additional experience to catch up in levels while you are playing the campaign, you will run what we will refer to as The Ghoul Route. You will run it when you are either finished with the campaign or skipped it entirely on the secondary character. This refers to a loop that you should run to the east of Kyovashad in Fractured Peaks, right outside the entrance to the Dead Man's Dredge dungeon (you can find an image of the route below this list). Be aware that if you are taking part in a group session, you will reset and continue to run through this dungeon until you reach level 25 or higher. This will continue until you have completed the dungeon.

It is highly recommended that you make your way to a Stronghold known as Kor Dragan, which can be found to the north-west of Kyovashad. You will not be required to finish the Stronghold in order to restart the encounter; rather, you will simply need to log out of your account and then log back into it (or, if you are currently in a party, leave the party and then re-invite each other).

After completing the Cathedral of Light Capstone Dungeon and setting the difficulty to World Tier 2, you will be able to access World Tier 3, which is the final difficulty level.
Change the difficulty to World Tier 3, and the first thing you'll want to do is the Tree of Whispers because it will give you your very first Nightmare Dungeon Sigil. You can change the difficulty of the challenge by clicking the World Tier 3 button. You should devote almost all of your attention to running Nightmare Dungeons at the highest possible level that you are capable of while keeping a consistent run speed. This should be your primary objective. This procedure will repeat itself for you until you have progressed to World Tier 4, at which point you will proceed to the next level. You have the option to enter the second Capstone dungeon between levels 60 and 65, providing you are confident that you are up to the challenge.

You will be able to access World Tier 4 once you have reached level 70 and have finished the Capstone Dungeon. You should be approximately level 65 or higher in order to attempt it, but it's not required. It is of the utmost importance that players take part in Helltide Events as soon as they become accessible on the global map. If you do so, you will be able to acquire the resources, items, and experience you need to progress in the game and develop your character.

Diablo 4 Ghoul Route: Leveling Up Quicker, Gaining More Experience, and Reaching World Tier 1
It is essential to keep in mind that this method of progressing through levels is not particularly exciting or enjoyable; rather, it is the one that is simply the most effective. You should not let the fact that it is the best use of your time convince you to take part in it just because it is the most effective use of your time. It is also important to point out that this strategy will not focus on the progression of Renown. This means that you are initially going to miss out on 5 Skill points, and you should build your character accordingly. It is also important to point out that this strategy will not focus on the progression of Renown.

Considerations to Make Before Ignoring the Campaign in Favor of a More Detailed Strategy
The campaign can be skipped, and the process can move on to the second step of the strategy directly. This is the approach that will be the most efficient. It is strongly suggested that you finish everything there is to do in World Tier 1 before moving on to World Tier 2, even if you believe that you will be able to finish World Tier 2 nearly as quickly as you did World Tier 1. This is because completing everything in World Tier 1 unlocks the ability to move on to World Tier 2. This will position you for the quickest possible clear time, so take advantage of it.

It is not uncommon for players to enter Act 5 with a lower level than they should have had as a result of rushing through the content of the game. This is due to the fact that players often rush through the content. You can probably expect to complete the quest between levels 40 and 42 at the earliest. As a result of this, it is extremely important to keep this in mind, as the Cathedral of Light Capstone Dungeon can be quite difficult for players whose levels are lower than 45.

The Stronghold of Kor Dragan, which is situated in the north-western region of the Fractured Peaks, is the location that is best suited for carrying out the aforementioned activity. You will need to log out of your character and then log back into them again in order to get rid of this. If that is the case, then you will still be required to come here to complete the remaining leveling requirements before increasing the difficulty to World Tier 2 and attempting to complete the Cathedral of Light Capstone dungeon.

Tier 3 on the global scale
Now that you have reached World Tier 3 of the game, it is time for you to shake things up a bit and try something new. After this, you will begin running Nightmare Dungeons with the goal of completing them at the highest possible tier without causing a significant slowdown to the overall speed at which you clear content. This new quality of gear has the ability to roll higher numerical values and additional modifiers in addition to those capabilities. It is possible that you will run into a problem in which you will be unable to upgrade your items due to a lack of the necessary materials. If this does occur, there is a chance that you will run into this problem. You have probably already guessed that we will have to take you back to Kor Dragan if you are still having problems after trying those other things.

Proceed to the next step of the process, which is to complete the World Tier 3 Fallen Temple Capstone dungeon. The difficulty level of this dungeon is 70. Despite the new difficulty, the overall strategy has not been modified in any way. You should make Nightmare Dungeons your primary source of experience once you have unlocked them and reached the point where you are able to complete them without any difficulty. You should also make Glyphs and Glyph experience your primary sources of gain.

An Interactive Map of the Mystery Chests Can Be Found in Helltide
In the same vein as the challenge that came before it, if you find that you are having difficulty, you should stop what you are doing, go back, and level up a little bit more before moving on to the next challenge.

It was mentioned at the beginning of this guide that if you rush through content like this in the name of efficiency, it can very quickly become repetitive and reduce the amount of fun you get out of playing the game. This is because you are maximizing your efficiency.