Just beat the Teostra + Lunastra quest on my second attempt, took me arounnd 40 minutes. Used Snowfletcher bow + full alfa Legiana set for Lunastra weakness to ice. I had to play around them moving together until they split up, then focused on the Teostra and farcasted away when Luna came. Eventually Teostra went to sleep at nest, chased after him and killed him there. Then i only had to 1v1 the Lunastra, which is still no easy task, but i agree with the bull*****that is her nova. However, with the usage of farcasters and playing defensively, i manages to beat her. She is so aggressive and agile, so much worse than any other elder dragon, she really likes to aggro you for far longer than any other monster, even ignoring your palico, while you try to heal. She's a pain in the ***, not an enjoyable monster at all, and all for a horrible looking armor set.