How can an NPC anti-Paladin mess with the party, without killing them?

[bob_the_monster]

She's there to deliver a message and assess the party's current battle strength / tactics for her master, a very high level lich wizard. Is it over the top to have her sunder items, perform dirty tricks, steal stuff, or knock people unconscious, perhaps kill party familiars/pets?

The NPC's main goal here is sociopathic self-amusement and to demonstrate their weakness to them. She's bored because she isn't yet allowed to kill them by the master's orders.

[master_marshmallow]

Hit them with her cruelties, with Word of Healing, she can do it from a distance for half damage, but full cruelty effect.

She could attempt to send her undead companion or try and raise some undead to throw at them, strengthening them and keeping them up by channeling negative energy.

[Jesuncolo]

Accompany him with a witch. Evil eye + Crackle + whatever save or suck.

Hello, -8 to Saving throws. Have fun.

[Darien Cedric Espoir]

make her the Lord of Darkness 3pp archetype. dominate them, make them do embarrassing things for her, then release them. haha.

[Claxon]

So, I detect some problems...

Why would a CE person like a antipaladin bother to follow the lich's rules or accept the lich's yoke.

Why would the lich decide not kill the party of interlopers? From the lich's perspective any possible threat should be eliminated as quickly as possible. That it ruins the campaign for the players shouldn't be of concern to the lich.

Showing the party they're weaker than the BBEG is an overused trope that is mostly annoying to the party and breaks engagement.

This is my personal opinion on the matter, and I'm sure others will disagree. But if I were your player I would be thoroughly confused as to why the great wizard lich wouldn't just off us at the earliest chance.