There was that fine hair she hadn't been splitting. Liliana was immortal in the same way (though not the same mechanics) that a vampire was immortal: ageless and unaffected by natural causes. But she could absolutely still be killed. Even at their strongest, Planeswalkers were not in general indestructible or undying and she was still less than what she'd been.

But she had no compunctions just eliding right over that!

"I didn't threaten you!" Liliana said, offended. "I couldn't even speak! And I certainly didn't invite you into my mind!"