Nell let Lua bind and tease her, as a reward because the drow slut behave. And while she's still locked in her chastity belt, Lua decided to pleasure her sexy Mistress with a small game. Nell is allowed to cum if she manages to hold the vibrator between her thighs. If she drops it... the pleasure stops. And only Lua knows what she'll do instead.
I'll suggest her to take the toy away right before Nell reaches climax, so she can experiment the cruel frustration she usually inflicts to us >3
Alts : no toy, no blindfold