Who could be in the ivory tower ignoring everything in the world beneath? Where is the oasis?

4606668 What is this? Some sort of a secrete code?

It is the name for the next chapter in multiple parts.
An ivory tower is an imagined structure where-in some-body is utterly isolated and thus unable to socialise or empathise with people outside the tower.
An oasis is a place in a larger arid region, most commonly a desert. An oasis is a watering hole ringed with palm trees and coconut trees. It is also understood as a place of safe serenity in a larger region of hubbub and bustle.
It appears obvious who is in the ivory tower. In the next chapter, we may see Celestia's thoughts on what is bothering Twilight.

4608310

It's the name of the next chapter.

Baxter, using the reply feature (the arrow at the top right of someone's post) will help you get more responses in the future.

4612164 I know what Ivory Tower and Oasis are. I just couldn't get what does this has to do with WHJT...

Yes. that's sound a lot like Celestia. But we although can say, that's Twilight is also in the Ivory Tower as well as Blue Blood...

As for the oasis I am lost .

4621566
I am certain the Oasis is Ponyville or Night Light and Twilight Velvet's house in Canterlot. It appears to exude a whiff of security.

4623825 Not sure about Twilight's parent's but the idea about Ponyville sounds plausible for me.

4626875 The Oasis could not be the Crystal Empire. It is too large, and should be considered a Haven.