Adding portals to your multiplayer maps adds an interesting pressure dynamic that isnt found in normal towerfall. The portals are used to create pressure and to force the players to move to avoid them, or to spend their resources(arrows/attention) dealing with them.

While custom quest levels aren't supported through workshops, due to the way workshop is set up currently, they aren't impossible to make, and with the existing knowledge of the games' files found on both Steam and the towerfall reddit, you can definitely make your own levels and Matt(the make of the game) has given permission to share the customized maps.

The portals found in the editor are for use with the Dark Portals variant in versus matches that spawn enemies into the stage as additional hazards. Death to an enemy counts as a suicide.