You can’t “host your own” it’s against Blizzard’s EULA to hold any Tournaments they do not give the go ahead to.
Section C. iv. of the EULA
“esports”: Use the Platform for any esports or group competition sponsored, promoted or facilitated by any commercial or non-profit entity without obtaining additional authorization from Blizzard or obtaining Blizzard’s prior written consent. For more information on obtaining appropriate authorization, please visit Blizzard’s website.
There are already streamers who have set up Classic dueling tournaments that were shut down by blizzard with a threat of a ban if they continued the tournament. They had to return the community donated funds that were to be the prize pool.