[chaos_alfa]

Originally Posted by Touko

That's what Zouken said, but he was obviously lying. We know Tokiomi's goal is to reach the Root (rather than achieving immortality), from several source. He was just trolling Shirou.

This is the part you meant, right?

Spoiler:

To give a daughter to the Matou family means giving us a foundation to achieve our goal. Tohsaka is well aware of that. We both have the same goals. We will both turn ourselves into monsters to achieve immortality."

"Immortality…?
You and Tohsaka's father used Sakura for something ridiculous like that…!?"

"Of course. The Holy Grail War has always been a ritual dedicated to that end. That is the only reason we cooperated, and I am the only one who still lives.
To use the Matou successor to achieve our goal in the far future."

And also, Zouken was lying in saying that the Ritual was dedicated for achieving immortality, while he knew its ultimate purpose was for reaching the Root.

To add to this.

Zouken probably isn't even aware that what he is saying is wrong because

Spoiler for Heavens Feel:

the pain of his decaying body is effecting his memory.

Like in how his true goal isn't actually immortality, but reaching the Root like any other magus.

(at least if I remember correctly, it has been some time since I played Heavens Feel)