I prefer the 1d4chan solution to Lucius:
As for actually killing him, Lelith Hesperax has canonically put a bunch of thought into how to kill him permanently, much like the 40k fanbase at large (I'm not saying she's a huge nerd, but I would point there's no canonical work that states otherwise). Apparently her theory is that if his armor is removed, he can't pull off his possession trick.
Amusingly, much like other nerds, Hesperax's plan has a few obvious holes in it. Specifically, her plan to capture and duel him is because she wants to face him in what she thinks would be the greatest duel ever.....which I doubt would actually be the case. After all, Lelith has been fighting in duels for who knows how many thousands of years and not losing, whereas Lucius has died so often his "kill me and I just come back" gimmick is widely known. He doesn't stand a chance in an even fight.
Techmarines are just as proud and vainglorious as thier fellow marines.
As for actually killing him, Lelith Hesperax has canonically put a bunch of thought into how to kill him permanently, much like the 40k fanbase at large (I'm not saying she's a huge nerd, but I would point there's no canonical work that states otherwise). Apparently her theory is that if his armor is removed, he can't pull off his possession trick.
Amusingly, much like other nerds, Hesperax's plan has a few obvious holes in it. Specifically, her plan to capture and duel him is because she wants to face him in what she thinks would be the greatest duel ever.....which I doubt would actually be the case. After all, Lelith has been fighting in duels for who knows how many thousands of years and not losing, whereas Lucius has died so often his "kill me and I just come back" gimmick is widely known. He doesn't stand a chance in an even fight.
Killed by an Astartes Techpriest who McGuyvered the kit from scratch in person with only on-site tools they themselves made?
Techmarines are just as proud and vainglorious as thier fellow marines.