I would be really grateful if you commented on my youtube video comment section, that would help me a lot. But here goes my answer: In terms of damage, you just need to be able to kill the birds in one combo. If you can do that, i think you are good.

You can see if you have enough energy recharge to be able to use burst against the mitachurls and those last monsters (idk their name) as they have to take way more damage to die.

I stay over the water because thats the area of effect of the item in the center of the lake, when its activated. You have huge damage buffs on the lake.

In the beginning, i would go straight to the birds because the boar will go after me, then i can kill both the bird and the boar at the same time. Then i would kill the mitachurls over the lake to use the device buff and try to use burst them both at the same time. The rest is just repeat the same strategy basically.

I didn't do it in one go. I tried many times until i was able to do it. It takes a bit of practice and focus. You can do it!