These commanders are so rare you might not have heard of them. They don't show up on EDHREC, and you won't find them in a normal Scryfall search. Each of these promotional cards had limited print runs, so if you didn't nab one when it first came out, you're probably out of luck.

If you did get one though... how would you build around it?

1996 World Champion

Nira, Hellkite Duelist

Kharis & the Beholder

Sol, Advocate Eternal

The Legend of Arena