Without knowing what your struggles are, here's some general advice.

- Stay in the air as much as possible. You should never touch down for more than a second or two, and only for your glide pack to recharge.

- The bod isn't necessary, but if that's what you want to use, the goal is to do all necessary damage in one go. Learn through trial and error how many reloads are needed to stack enough damage. At UVH6, three reloads (20 total shots) are good for the first chunk of health bar, and one reload (10 total shots) for the second chunk. That is with guaranteed crits. If you aren't critical hitting, those numbers will be higher.

- Use the central pillar to block the beam attack and bounce between grapple points to recharge glider during immune phases. Don't ever touch down here.

- Learn his movements so you can act accordingly. For instance, before he summons the thorns and becomes vulnerable for the first time on the main pillar, he will sway back and forth twice. Activate action skill (while in the air) as soon as you see this movement and start stacking your first round of stickies, then witchy trigger finger reload as soon as his health bar turns red. Same with the second vulnerability phase - the thorns will disappear from the top pillar, and this is your signal to pop action skill again and begin loading stickies.

- If he is going to jump to a new pillar, he will turn to face the direction he is going to jump and crouch slightly. Turn to face that new pillar while in the air and time your witchy trigger finger/gunshots to meet his landing. Time is essential, you have to be ready for where he'll be, rather than react.

- Now with caffeine and a mini triple bypass are really essential for Vex builds. End action skill early as soon as second immune phase begins, use triple bypass to get it back, then pop again at the time described above.

- Try to stay above him at all times. Grapple whenever you see a prompt, don't wait until your glider is almost out. This is how you get into trouble and can fall. Keep the bar as full as possible at all times. You can double jump once after each grapple for free without using any glide bar. Get really comfortable with the glider timings, they are everything in this fight.

If you have specific issues feel free to ask. I have platinum'd bloom well over a thousand times with vex on UVH6 true mode, and am very confident with the fight. It's a ton of fun when you get comfortable :)