How do you beat the TWO HORNS guild quest?

I'd take any water attribute weapon, I recommend frost edge(SnS) You will need cool drink, herbs, potions, mega potions, and maybe some lifepowder. Take with you also sonic bombs (gunpowder and screamer)

^ they can, make the difference between doing the quest, and failing it. I bring along as many as I can, so I bring 10 sonic bombs, 20 gunpowder and 99 screamers. Then I also bring fireherbs and nitroshrooms, to combine to make gunpowder. This way, I can have plently on sonic bombs to use.

Sonic bombs are used when the diablos digs, throw it when the tail just disappears. It will get the diablos stuck in something similar to a pitfall trap. It means you can get plently of hits on on the helpless thing. It won't work when the diablos is raging, so don't waste them. It helps to chop off the diablos' tail as well, it can get annoying...

Make sure you ration your items 50:50 so you have enough of everything to take on the other diablos. And keep track of the time, you have 25 mins each, to kill the diablos'.

Attack the diablos on the leg when it is about to charge
Block if he is charging form far away, he turns quick, so it is easier to block than try to dodge it.
Use his horns to get then stuck in the ledge. Don't hack at his horn from the ledge when he gets stuck though, because once you have broken both off, you can't do it anymore. Get him stuck, jump down, hack at his leg, jump back onto the leg when he gets unstuck, repeat.

All I can think off ^.^