How can i defeat Legendary Tiki?

Slaying hammers, Naga/Divine Naga tomes, fast green mages, your own L.Tiki, potentially A.Tiki with Breath of Fog if you invest enough in her atk

Whats a god to a slaying hammer

You can't, she is invincible.

Anna.
Her res is higher than you think.

Anyone with dragons effectiveness can probably end her. My Kliff can kill her. She's actually not all that tanky especially if you double her.

Bartre, Julia and Deirdre say hallo.

Bartre
Cherche
Deirdre
Nino
Raven
Titania

From seeing some of these posts........ personally i say Sheena is your best unit to take on L!tiki. Her res can hit mid 30's, she can have a slaying hammer if you give her one, and she is a F2P accessible unit with a respectable amount of hp to take some moonbows if needed.