Maybe it's old news but I noticed recently that when I have mounted champion atma, my luopan's HP doesn't drop; like at all.
I have to test this more if other atma affect the luopan, such as HP+ ones or possibly evasion, since those would help too. Maybe ducal guard works on it too since technically it IS considered a pet. You can check it's HP with <pethpp> after all.
So yeah, fun little tidbit for any Geomancer out there who goes to abyssea.