I need pointers on Barthandelus.

[docta fizz]

But here's the thing- we can't rebuff because the magic bomardment kills the team too quickly. This is 9 times out of 10, one time I got lucky and was able to get to the last stage of the fight before getting killed by Destrudo. I've been doing SOME grinding and it's been sucessful but doesn't seem to make a difference. I'm losing interest in this game quickly because this boss fight keeps destroying me and I don't know what I'm doing wrong.

Well if you don't have a ridiculous amount invested into your weapons now is a good time to change a little something up.
I have the healing rod on vanille for this fight, it gives you the sythesize abilities of magic wall.

synth spoiler(SPOILER)
Hope - Hawkeye
Sazh - Deneb duelers
Light - Edge carbine
Items to include: Gold bange, diamond bangle, Magicians mark, shaman's mark, rune bracelet, auric amulet and I'm sure there are others

How it works is you use any combination of these as accessories and weapons on a character and you get "magical Wall"

2 item = 5
3 items= 10
4 items= 20
** note your weapon counts as an item **

If you put some of this on your healers it should give them what you need to survive