You can avoid getting the first Crem Guard by getting the boss to 70% before the Guard's portal appears.

My strat:

Take power sigil, drop dots (hail, caltrops) and poison inject when the boss appears. Use ultimate, block the skull, and continue rotation on your DW bar. Run to him after he ports away and interrupt.

Will work if you have the DPS. If not, it's best to save your ult for the Crem Guard. I activate Vigor for the heal over time and use the Ballista ult to burn the Crem Guard down from far away. I farm this on my StamDK and I use Corrosive Armor to deal with the Crem Guards, but I've used Ballista too and it works fine.

At the crystals phase, if you have the DPS and experience you can burn all three down before the soul churn damage becomes too much to handle. You can take the healing sigil before porting up. I find it best to get one and a half crystals down, sometimes two, then let the boss throw me off the stage. I go down and take the healing sigil (or defense sigil if healing was taken before) and use my ult to kill the Crem Guard waiting below.

I port back up, and this resets the soul churn damage so I'm able to kill the last crystal easily.

You should have another ult by now. Make sure to interrupt the boss asap if you don't have the defense sigil. Drop your dots on him, and grab the gold ghosts. Having the haste sigil will help with this. If you don't grab all three, you'll have a rough time if you hate Crem Guards (and everyone does.) Another Crem Guard WILL spawn after three gold ghosts, whether you grabbed them or not. Make sure to kill those slow walking summoners too, you do not want them spawning a bone colossus.

After you grab the third ghost, be prepared for the Crem Guard. You'll see the portals spawn after the third gold ghost. Activate the synergy to stun the boss and guard and kill the guard asap. Then drop dots on boss and continue rotation and hopefully you should kill him or be close to killing him by then.

This was the roughest fight on my first time. Actually, still the roughest fight for me after completing vMA 5 times, but it definitely gets easier with practice.

slot ballista and use it on the crematorial guards, that it at least what I do on my stamsorc

Yeah I hate the Crem Guards, but the fight would definitely be too easy without them. There aren't a whole lot of threats in stage 9 other than them, the ground spears are easy to avoid, the ghosts can be annoying to run into when there's so much going on but they're pretty easy to avoid, and the boss doesn't do much but stun you and cast his necrotic swarm that needs to be interrupted (or else you're dead), and the summoners die quick.

The Crem Guards are fast and do a ton of damage so it's best to save ults for them. Ballista is good because you can burn them down quick at range and kite them. Unfortunately that's how it is. With practice and the DPS you can complete this stage much easier without seeing the Crem Guards.

The first try is always the roughest. Took me three days to beat the final boss and a lot of screaming at my computer. But keep at it, each time you do VMA it'll go by a lot quicker and easier. Soon you'll be able to farm it in an hour or less with any class. You'll know what to expect in each stage and each round and be able to deal with everything with fewer mistakes.

Practice circlestrafing him. If you stand on his shoulder and rotate around (so that he does his slow pivot instead of whipping around to target you) you can stand in melee range and shred him unscathed.

It's an incredibly frustrating move, until you get the hang of the circlestrafe, and then it's a nonissue.

I don't have super high DPS on a lot of toons, so I have to kill 1-2 crem guards to get Valkyn to go upstairs. With practice, it's relatively easy to even do the circlestrafe right next to the boss so you can keep your ground dots ticking on both.