Since the move to Discord and creation of the Nexus Guide, dueling has been done with bot commands sent on the DM channel to the bot. All in all this has worked very well and is much faster than dueling had been in the past. If does have the down side of needing to bounce between channels to communicate with both the room and the bot. The command scheme is also felt to be awkward by some.
The Duel Wizard presents another avenue for getting your duels in. Click the "Launch" button below (assuming you are logged into the site) and launch the tool and duel from there. It is slightly slower than communicating directly with the Nexus Guide, but comes in a compact window you can set up next to your Discord client so you will no longer need to switch channels and can duel with the click of a mouse. Give it a try and send any comments or suggestions along to the staff if you have any.