Rod of Ages on Nidalee

It's more of a jungle nidalee item, gives her more durability

I've only seen it done out of the jungle, and only if you need the extra tankiness to survive jumping in to execute someone after a good spear.

Traditionally, no.

Very mediocre. I think even champions like or have more reasons to buy this than her

ive seen it rarely it isnt terrible

It is a must buy, no explanation should be needed. If you don't buy it, you will be killed solo by the enemy marksman before you complete WEQ in cougar form come mid - late game.

Unless you plan to never go in after landing a spear, of course.

I personally think Seraph's is a stronger item on her, because it offers a lot of the same things just better scaling.

The reason people like RoA is that it gives a lot of durability for if/when she goes into a fight in cougar form. Seraph's has more conditional durability from the shield, but it stacks quickly and gives more mana and AP.

Flat mana regen and higher ap generally better. Morello or Seraphs highly recommended over RoA. I like Seraphs for jungle because you get CDR from Magus and Morello for lane because you would otherwise miss the CDR.

A ROA on nid feels like more of a top lane strategy to make her tankier in order to survive the burst and stay in the fight. If that's the case, you can go AP/Hybrid nid top. Basically it's the same thing as a normal AP nid build, but your early and mid game is easier to survive against tankier champs. Basically same masteries, standard AD runes and go double doran blade + Ice born gauntlet( you can get triforce too, but I feel like the mana is more helpful here). Followed by the normal AP build (Dcap, Void staff, etc.)