The Official Monster Hunter 3 Ultimate Topic

Any tips on killing Aggy? All my swords are bouncing off him.

I'm assuming you're talking about Agnaktor, but I'm not sure which one, so I'll just detail both. For regular Agnaktor, his igneous rock armor melts every time he gets back into lava, this includes walking through it or digging down into the ground into the magma below. Attack him after he has done this and with enough hits, you can damage certain areas on his body and will no longer be able to form igneous armor on those parts--these parts include: his beak, all four of his legs, his tail, and his spinal fin. If the magma on his body cools and forms his armor, it's best to just focus on dodging and avoiding him until he melts it off again.

For Glacial Agnaktor, it's sort of the same deal but a little more difficult. Instead of armor forming over time on its body, the frozen ice armor is instantly on his body from the start of the fight or after anytime he dips himself into the ice below. You can break his parts to make it so he can't form armor on those parts, and they are the exact same as regular Agnaktor. The only thing is, you have to wait a few minutes for the ice armor to actually melt off his skin, OR there are two other ways: one way includes just hitting the armored parts and bouncing off over and over until it shatters, or if you bring a Fire elemental weapon (which you should, considering he's weak to it), hitting the ice armored areas with the Fire weapon will melt the ice faster.