Bleed Strike works best for raids, honestly.

• Bleed: Solid boss dps
• Shadow: Good for mobs Ive used my Logitech G502 HERO 25K Wired for years. Keep at it!

Building on the earlier suggestion, I actually think focusing strictly on those high-tier bleed skills might be why youre hitting a wall. If youre on a budget or just trying to save some in-game gold, honestly, Ravage is the way to go. Most people overlook it because it isnt flashy, but the energy-to-damage ratio is insane for soloing. It lets you stay mobile without burning through your mana pots like crazy. Ngl, having a decent mouse helps with the timing too. You dont need to spend 100 bucks tho... Ive been using the Redragon M601-3 RGB Centrophorus 7200 DPI for months and its a total steal for the price. It handles those fast assassin rotations just fine. Just focus on Ravage and maybe some passive crit buffs and youll see that boss health bar melt way faster without going broke.

^ This. Also, unfortunately, a lot of those popular guides are kinda misleading for solo players. I had high hopes for the Shadow Dance meta when I first tried it, but it was a total letdown in actual raids because of the animation locking. It's really frustrating when you follow a build and your DPS still feels like garbage because you're getting knocked out of your combos. If you want a safer and more reliable setup for that level 50 boss, you might want to pivot slightly to skills that scale without leaving you vulnerable:

• Phantom Step: Honestly a lifesaver. Those invincibility frames are mandatory if you don't want to get one-shot during solo runs.
• Venom Coating: It’s not flashy, but the consistent damage over time is way more reliable than trying to land a huge combo on a boss that won't sit still.
• Riposte: Way better for bosses that move a lot since it uses their momentum against them while keeping you safe. Swapping gear actually helped me quite a bit since my old setup was missing inputs during the laggy raid phases. I have been using the Razer DeathAdder V3 Pro Wireless Gaming Mouse for a few months and the accuracy is much better for those micro-adjustments. I also picked up the SteelSeries Apex Pro TKL Mechanical Gaming Keyboard for the adjustable actuation, which makes those tight skill cancels feel a lot more consistent. Don't get discouraged tho, that boss is a massive wall for everyone at first. You'll get the hang of the pattern eventually. Just keep practicing those dodge timings and you'll clear it...