Secret mission 5

[methosrocks]

Am i missing something?
I've done literally exactly what it says, attacked his legs while it's standing up yet noting happens.

[Simon]

Here
https://www.trueachievements.com/a25122/secret-mission-5-achievement

[darth.crevette]

Some of the secret missions have very weird timing/requirements. For this one, I got the "Great" while the boss was being levitated in mid-air by Rita's gravity well, so there's no way it was actually standing up on its legs...

Keep in mind it also has some kind of "super armor" though, so a single hit might not do the trick. People seem to do it easily enough with just Azure Edge though, so I don't know.