For the Dominaria previews, many people have been confused on the symbol for legendary cards.
For anyone who may not pour over any information given to us, it is the top of a pillar with a slanted bottom, seen below:

Now, for ancient Magic players like me, we know that this is the set symbol for Magic’s third set, Legends. From 1994. 24 years ago. Even though I have been playing nearly that long, and own many of the very valuable cards from the set, I still don’t quite understand why the symbol is the top of a pillar.
Flash forward to 2014, where the Duels of the Planeswalkers video game introduced legendary cards for the first time. Duels of the Planeswalkers has icons for evergreen keywords, and most of those match up perfectly with MTG:PQ. The chosen icon was a crown, with radiating rays coming off of it, seen below:
To me, this symbol makes sense and has meaning behind it. It shows that the individual has put in the work and survived rough experiences to earn a crown and stand out among those in a crowd.
Additionally, this was also the set symbol for From The Vault: Legends, released in 2011.
Also, with Dominara, Legendary cards were given crown-like flourishes on the top of their card frames for the first time, setting them distinctly apart from other cards.
@Brigby I would like to call your attention to this, if only to escalate it up. Currently, it feels mis-aligned with the direction of other Magic products. Even though it is closed, you have my permission to group it up with the May Q&A session.