Lillia excels at kiting and dealing sustained damage with her high movement speed and skill range. Avoid direct fights; instead, poke enemies down gradually.
Look for teamfight opportunities by landing skills to activate her AoE sleep ultimate, and use Zhonya's to bait aggro and survive critical moments.
Key to her playstyle is building HP-scaling AP items like Liandry's and Demonic Embrace for both damage and tankiness, allowing persistent harassment.