The unicorn is a bit of a poor prize for the Tsar tournament.
This is something that you win very easily from following clues.
Anyone playing for even a fairly short while is likely to win both the black and white version of this.
The prize for this should be a more unique mount like the Boar, the Brown bear, the Stag or maybe even the Black Bolt which is very rare.
If people already have the prize mount that is on offer then they should be able to win a different one.
But the Unicorn shouldn't even be considered as a prize as it is too common. The prize should be more special.