Sensei TopSensei Top on Linux and the Steam Deck
Arena and Magic Online both run on Linux, through Proton or Wine. Sensei Top runs beside them as a Linux app of its own: an AppImage that updates itself, with nothing to set up in the game's prefix.
A Linux app, not a Windows one under Proton
Sensei Top runs outside the game's Proton or Wine prefix, as a program of its own. It only reads the log Arena writes there, and never touches anything the game owns.
Finding Arena's log
Under Proton or Wine, Arena's log sits deep inside its prefix's drive_c folder. The app looks for it in Steam's libraries, in $WINEPREFIX, in the prefixes Lutris, Heroic and Bottles make, and in ~/.wine. If yours is somewhere else, open Settings, under Sources, and set the Log file there; the install guide says where it is.
Install
Download the AppImage, allow it to run as a program in the file's properties, and double-click it. On the Steam Deck, do this in desktop mode. The help page has each step, and a .tar.gz for a system where the AppImage will not run.
Magic Online too
Magic Online under Wine or Proton writes its game logs inside that prefix's drive_c folder. Give the app that folder, with your name on Magic Online, and its matches join Arena's on the same dashboard. Sensei Top for Magic Online