Things you can do with Bard's Ultimate

• Set up Wombo
• Disengage From Wombo
• Protect From Wombo
• Catch people out
• Freeze enemies so allies can escape
• Shield allies from a DoT like Ignite, Death Mark, or Infectious Period Blood
• Protect a tower from falling when in another lane.
• Protect nexus towers giving your team an extra 2.5 seconds to revive.
• Freeze enemies so champs like Sion, Vi, or Azir can escape with their abilities that would otherwise collide with enemy champs.
• Freeze Baron or Drake to prepare for a steal.
• Shield an ally from an Ashe / Draven / Ezreal / Jinx / Ziggs / Pantheon / GP Ult.
• Kill an ally that wont stop bitching.
• Prevent an enemy from teleporting by ulting the tower, minion, or them when they are teleporting.

Or the most popular use in Bronze...

• Fuck over your team because of your inability to use a champion that requires more mechanics that right clicking and pressing R