Bubble Trap Tactics

A video about tactical ways to use the bubble, it may save you, deal a decisive defeat on your opponent, or at least educate you on the dangers of potential falling into a trap.
You can do this with an empty city with allied reinforcements rushing in to have overwhelming defensive numbers. This way everyone shares the cost of healing and you don't have to shoulder the burden alone.
Always Bubble first if you are attacked, then switch heroes. The entire time in this video I was on my defensive hero set up so there was no hero switching during battle.

[@908Dannyboy]

What game is this?