At the end of the Parsha, after everything was commanded - the Aron, the Shulchan, the Menorah, the big Mizbe'ach, the Mishkan itself and even the clothes of the Kohanim and how to prepare them for work - suddenly after all this, the Torah decides to tell us that there's also a small Mizbe'ach inside, that is meant for essence.

Why does the Torah bring it only now? After everything?

Shouldn't it be brought together with the Shulchan & Menorah?

What's the (incredible) purpose of this Mizbe'ach?

And how does this all connect to Purim?