Bitch you’re a BUM. 3 kids and live with your MOTHER. You ain’t doing shit. Applying 0 pressure. You make more money than someone but wtf does that say right there? ASKING FOR MONEY🤣 broke ass yellow ass teeth bitch. Close your legs. Your poor mother asked you to file for food stamps because your fucking kids are eating all HER food. Duh she’s gonna ask you to apply for food stamps.
Reposting with the babies faced crossed out ***

I did some research on how the order of buff synergies, because I couldn't find anything about them online. After doing 2-3 short runs to figure out their connecting paths, I figured I'd make a build that uses all buffs (except Haste, because I hate moving too fast).
The result was pretty intense! I managed to get to OL12 without any issue, and was able to facetank it while being AFK (the gif is OL11 but I got to OL12 later on). The run is literally still on-going in the background as I'm typing this guide, so I'm pretty convinced it works.

The Build

Skill selection
Runes
Have an exact selection of skills, combined with the Prowess rune to ensure you have every buff, or a way to synergize into them, made stronger by the Synergetic rune. Combine with Earth skills because Earthquake is easy damage and Earth Shield provides immense healing.

Core mechanics

Contrary to my other builds, the core of this build isn't a particular skill, but rather scaling buffs to such a degree that your stats essentially don't matter anymore. In order to get all buffs, we need to use synergies to get them. The only alternative is to take skill that grant us the buff directly, but that would require an insane amount of Skill Mastery runes.
If we want to get the synergy passives, we must have 2 sources for the "start" buff. For example, if we want the synergy passive that grants Bulwark when we get Finesse, we must have 2 sources of Finesse already. Once you get a synergy passive, that passive now also counts as a source for that buff, so you can daisy-chain them to get more synergies. Additionally, we can get Prowess from a Rune, which also counts as a source for the synergies.
Combining all buffs (except Haste), we can get damage, crit chance, crit damage, multicast, armor and block. We can get those stats to such a high degree, that choosing any of these as an actual reward becomes borderline useless. If you've already got 2000% increased damage, getting +15% as a rare reward doesn't do much anymore.
What remains is cast frequency, (some) multicast, health and experience. We also need a bit of movespeed to make it a bit more comfortable during the earlier levels, but as we'll completely stop moving around OL8, we don't need too much of it either. Even though we also get multicast from the Finesse buff, it's the one buff that we don't have any synergies towards so it doesn't get quite as high as the others.

Breakdown

This skill uses the Unexpected Arsenal rune to allow all weapon-specific skills to be selected freely.
Skill Selection
For the Bulwark (block) and Finesse (multicast) buffs, we use Whirlwind and Double Slash. Double Slash has the added benefit of also applying the Debilitated debuff on enemies, reducing their damage dealt. Since both skills grant both buffs, we immediately apply for both synergies. However, Finesse synergizes into Bulwark, which we already have 2 sources for. Still, more block is never bad, and it provides an extra chance to trigger Bulwark's synergy, which goes into Aptitude (crit damage). This is our only source for Aptitude, so the extra chance to trigger it isn't unwelcome.
Whirlwind is almost exactly the same as Double Slash, just without the Debilitated debuff.
For Prowess (damage) and Resilience (armor), we primarily use Heavy Strike and the Prowess rune. Like previously mentioned, the rune counts as a source of Prowess and allows us to synergize into Resilience. That synergy passive then becomes the second source, allowing us to synergize Resilience into Form (crit chance).
Heavy Strike also applies Bleed, but we don't actually scale it so it doesn't do much in the bigger picture.
To make the build actually deal damage, we include Earthquake, which is one of the highest damaging abilities in the game, due to the Brittle stacks it applies and the Colossal buff.
Brittle stacks on enemies increases the damage of future hits by a flat value. This means that you're better off using a skill that does a ton of small hits, instead of using slow but heavy-hitting skills. Earthquake itself is a skill that does a ton of small hits, which means it both applies a lot of Brittle, and take great advantage of those stacks. Further more, as you get higher level and start casting Earthquake more often, you'll both apply more Brittle and hit more often, which makes Earthquake particularly powerful.
The Colossal stacks provided by Earthquake also make Earthquake itself hit a much bigger area. With enough multicast and skill-chaining, we can get Earthquake to cover pretty much the entire arena. This is another way in which casting Earthquake faster make Earthquake more powerful in general.
https://preview.redd.it/nacvbt2cyt1d1.png?width=689&format=png&auto=webp&s=c830d93242cc00dd7ab3cf8fb1cb194f8c9bb53f
An easy second choice for an Earth skill is Earth Shield. Not only does it also provide another source of Resilience to allow us to synergize Form from, it also provides massive amount of healing. With the amount of block and armor this build is already stacking, this healing can make us borderline immune to anything but one-shots if we get enough multicast and skillchaining.
https://preview.redd.it/avc1bdtpyt1d1.png?width=395&format=png&auto=webp&s=b7891025b7e59fe2ffeaeaa764a82c5ca2c900ed
For our 6th and final skill, we use Scent of Blood. We've got a pretty big stack of Finesse building and Scent of Blood is just an easy stack of Cast Frequency. It also creates a feedback loop where we get Finesse stacks from attacking, but Scent of Blood makes us attack faster, resulting in more Finesse stacks, make Scent of Blood stronger, and so on. This makes scaling Scent of Blood slow at first, but once it picks up, it is easily maxxed out.
Do be aware that the Cast Frequency provided by Scent of Blood doesn't apply to Scent of Blood itself. You'll need to scale some skill-specific cast frequency for Scent of Blood, and keep an eye out for any Duration passives as well to get 100% uptime.
https://preview.redd.it/akimp052zt1d1.png?width=397&format=png&auto=webp&s=51109cb4fadbdd8099315a8788795c64b451f546
Mechanics
Skill-chains
As always, skillchaining is the main way to scale the build, as it allows you to bypass the long cooldowns. The most important one is Swing-to-Earth, since we really need a ton of Earthquake and Earth Shield casts to get end-game damage and healing. Swing-to-Slam is also fine for getting more Prowess and Resilience stacks.
Synergies
Synergies are really what makes this build work. It's the best way of scaling our buffs into the ridiculous amounts. There's not much to be said about them, since they're just passive rewards, but they are on par with some legendary rewards for this build.
Skill Choice
The Earth kills I chose are largely because Earthquake is mega-OP and Earth Shield honestly is as well. You could probably swap them out for Holy skills without losing too much, since they also provide some healing, but I don't think you'll be able to deal as much damage. If you don't mind losing the healing, I doubt there's a skill you couldn't make work with this setup.

Rune choice

https://preview.redd.it/7n2ha8be0u1d1.png?width=368&format=png&auto=webp&s=d4e4c319b8d3f794cd7a214c5b6d6cc30769c593
Versatility Runes:
It's the usual combo of Endless Refill and Reroll Mastery to get easy skills selection, and we need Unexpected Arsenal to get acces to Heavy Strike. I wanted Heavy Strike since it's fast, but it's not a requirement for the build specifically.
You could swap out Unexpected Arsenal for anything you want, but then you need to change Heavy Strike for any other skill that at least grants Prowess. I'd recommend Armor Shatter. It's a bit slower, but it does provide the Shattered debuff, which might be nice.
Tenacity Runes:
The most important one by far is the Divine Legacy rune, which is (in my opinion) easily the best rune in the game. By cleverly saving and using your locks only at every 25th level, you can get 3 legendary passives every 25 levels, which is just crazy. This is probably true for almost every build, so you'll see this section in a lot of my builds.
Synergetic is super important for really getting the most out of the buffs you get from your skills, as is the case for any build that focuses heavily on buff or damaging debuffs.
You need the Battle Proficiency rune for triggering the Prowess into Resilience synergy, but that synergy isn't mandatory for the build to work since Earth Shield already grants Resilience. It's probably the best choice, but you can swap it out as needed.
Critical Mastery is super effective for our build since we can reach around 1000% crit chance at our highest point through Aptitude stacks. That's an easy extra 250% extra crit damage, which is pretty significant.

Stat priorities

These are the priorities for "basic" stats. Skill chain, type-synergies ( like "more damage per ice skill for non-ice skills", and legendary rewards are almost always better.
Prioritize in order:
Buff Synergies
Any buff synergy is good, even those that provide armor or block. Buff Synergies are so good, I personally consider them on-par with several Legendary passives don't do as much for our build (like Physical Damage for example).
Health
It's a bit weird to have Health listed this high, but in reality, we really don't need much else. Our buff provide such insane base stats, that we really don't need to worry about our damage output.
Rest
You might want to get some Cast Frequency or other stats at first to get the build going, but it's really not necesary to overinvest. It might not make your start the quickest, but this is a marathon-build, not a sprinter. Likewise, you'll probably want some movespeed to make dodging easier, but you won't be need to do much dodging in the end-game, so don't go overboard. Increased Experience is honestly pretty good for this build, since most of your power will come from the Legendary skill-chain and multicast passives and boosting Scent of Blood to get your cooldowns lower.

That's the build!

It's not very suprising that stacking a ton of buffs would result in a killing machine, but I didn't quite expect to be so unkillable. This was definitely one of the more fun builds to do, since I had to figure out which buffs synergize to what and which skills to take to get the daisy-chain started effectively.
In the GIF that I linked at the start of this post, I actually did the build semi-wrong, since I didn't take the Prowess rune (even though I intended to at the start). I only later noticed that it was missing, and only then found out that Earth Shield also provided Resilience, so that was pretty lucky for me. Fortunately, you guys have this build so you don't need to make the same mistake I did :)
If you haven't seen it, please have a look at my previous build, the Conflagrate Barbarian.